This list of largest reptiles takes into consideration both body length and mass of large reptile species, including average ranges and maximum records. The league comprises predominantly living crocodilians reaching a length of  and a mass of  or more. It is worth mentioning that unlike the upper weight of mammals, birds or fish, mass in reptiles is frequently poorly documented, thus subject to conjecture and estimation.

The saltwater crocodile is considered to be the largest extant reptile, verified at up to  in length and around  in mass. Larger specimens have been reported albeit not fully verified, the maximum of which is purportedly  long with an estimated mass of .

The following table below lists the 15 largest extant reptile species ranked according to their average mass range, with maximum reported/reliable/estimated mass also being provided.

Overall League

Lizards and snakes (Squamata) 

 The most massive living member of this highly diverse reptilian order is the green anaconda (Eunectes murinus) of the neotropical riverways. These may exceed  and , although such reports are not fully verified. Rumors of larger anacondas also persist. The reticulated python (Malayopython reticulatus) of Southeast Asia is longer but more slender, and has been reported to measure as much as  in length and weigh up to . The Burmese python, a south-east Asian species is known to reach up to  and weigh as much as  and is generally among the three heaviest species of snakes. Several other species of python can reach or exceed  in length and  in weight. The fossil of the largest snake ever, the extinct boa Titanoboa were found in coal mines in Colombia. This snake was estimated to reach a length of  and weighed about .

Among the colubrids, the most diverse snake family, the largest snake may be the keeled rat snake (Ptyas carinata) at up to . The Indian rat snake (Ptyas mucosa) is also very large with maximum sizes of up to , making it the second-largest species in the genus Ptyas. The Tiger rat snake (Spilotes pullatus), which usually grows to about , has been reported to reach up to , ranking it among the largest colubrids. The genus Drymarchon also contains some of the largest colubrids such as the Eastern indigo snake and the indigo snake (Drymarchon corais) which can both reach lengths of more than . Few other species in the colubrid family (such as False water cobra, Brown tree snake and Pseustes sulphureus) can reach lengths of , but they are relatively slender and generally do not exceed  in weight. 

 The longest venomous snake is the king cobra (Ophiophagus hannah), with lengths (recorded in captivity) of up to  and a weight of up to . It is also the largest elapid. The second-longest venomous snake in the world is possibly the African black mamba (Dendroaspis polylepis), which can grow up to . Among the genus Naja, the longest member arguably may be the forest cobra (Naja melanoleuca), which can reportedly grow up to . The King brown snake, reaching lengths of up to  and weights of  or more, is the largest venomous snake in Australia. The Yellow sea snake (Hydrophis spiralis) is the largest of the sea snakes growing up to a length of . Few other elapids can reach or exceed  in length and  in weight.

The Gaboon viper, a very bulky species with a maximum length of around , is typically the heaviest non-constrictor snake and the biggest member of the viper family, with unverified specimens reported to as much as . The Eastern diamondback rattlesnake is nearly as large, with the maximum length being  and maximum weight being . The rattlesnake genus Crotalus, which includes the aforementioned eastern diamondback rattlesnake and western diamondback rattlesnake (Crotalus atrox), reaches a maximum length of , and according to W. A. King one large specimen had a length of  and a mass of . The third largest rattlesnake is the Mexican west coast rattlesnake (Crotalus basiliscus), which reaches  long and  mass, and one captive-raised male was weighed at  in 2020. While not quite as heavy, other members of the viper family are longer still, the South American bushmaster (Lachesis muta) and Central American bushmaster (Lachesis stenophrys), with a maximum length in the range of , with the former being considered as the third-longest venomous snake in the world.

 The largest of the monitor lizards (and the largest extant lizard in genera) is the Komodo dragon (Varanus komodoensis), endemic to the island of its name, at a maximum size of  long and , although this is currently the only record that places the mass above . Crocodile monitor (Varanus salvadorii) is probably the longest living lizard, known to grow as much as , with reported lengths of up to  and weights of up to . The Asian water monitor is also one of the largest lizards in the world, with sizes of up to  and reported weights of up to . Few other species (such as perentie and nile monitor) can reach or possibly exceed  in length and  in weight. The prehistoric Australian megalania (Varanus priscus), which may have existed up to 40,000 years ago, is the largest terrestrial lizard known to exist, but the lack of a complete skeleton has resulted in a wide range of size estimates. Molnar's 2004 assessment resulted in an average weight of  and length of , and a maximum of  at  in length, which is toward the high end of the early estimates.

 Iguanas are very large lizards, some of which can reach lengths of up to 2 m (6.6 ft) and weigh more than . They are the largest lizards after some large species of monitor lizards, and the largest lizards in the New World. Iguanas vary considerably in size and form, but even the smallest lizards in this family are still quite large. Many sources describe the green iguana (Iguana iguana) as the largest iguanid, often reaching lengths up to 1.5 metres (4.91 ft) and masses of , and with a maximum length of 2 m (6.6 ft) and a mass of  and in some cases even . However, the heaviest species in this family is the blue iguana (Cyclura lewisi), with a total length of up to 1.5 m (4.91 ft), a SVL of 51–76 cm (30 in) and a mass of up to  It is the eighth-heaviest and largest extant lizard. Other large species in this family include the Galapagos land iguana (Conolophus subcristataus), with a length of about 1.5 m (4.91 ft) and a mass of up to . It is the second-heaviest iguanid after the blue iguana and the ninth-heaviest and largest lizard in the world. Another large species from the same genus is the Santa Fe land iguana (Conolophus pallidus), reaching a SVL of  and a mass of . The Galapagos pink land iguana (Conolophus marthae) have snout-vent length  and the mass of . The marine iguana (Amblyrhynchus cristatus) is also among the largest iguanas in the world, and the largest reptile on Galapagos Islands after the Galapagos land iguana, not including turtles reaching a maximum total length of 1.4 m (4.59 ft), a SVL of from 12 till 56 cm (from 4.72 till 22 in)  and a mass of from  depending on islands.
 The largest extant gecko is the New Caledonian giant gecko (Rhacodactylus leachianus) of New Caledonia, which can grow to 14 inches in length. It was surpassed in size by the extinct Kawekaweau (Hoplodactylus delcourti) of New Zealand, which grew to a length of .

By far the largest-ever members of this order were the giant mosasaurs (including Hainosaurus, Mosasaurus, and Tylosaurus), which grew to around  and were projected to weigh up to .

Tuataras (Sphenodontia) 
The larger of the two extant species of the New Zealand native tuataras is the Brothers Island tuatara (Sphenodon guntheri). The maximum size is  and .

Ichthyosaurs (Ichthyosauria) 

Some of these marine reptiles were comparable in size to modern cetaceans. The largest ichthyosaur was the Late Triassic species Shastasaurus sikanniensis, at approximately  long and  in weight. This massive animal, from the Norian stage in what is now British Columbia, is considered the largest marine reptile so far found in the fossil record. However, in 2018, a specimen from Lilstock was discovered to be 25 percent larger, approximately  in length, making it the largest marine reptile to have ever lived, with some believing to even dethrone the blue whale in size. Shonisaurus popularis is another enormous ichthyosaur. It reached  in length and  in weight. Cymbospondylus youngorum is the largest Middle Triassic ichthyosaur, with  in length and  in weight.

Pantestudines

Turtles and tortoises (Testudines) 

 The largest extant turtle is the leatherback sea turtle (Dermochelys coriacea), reaching a maximum total length of  and a weight of . The second-largest extant testudine is the Loggerhead sea turtle. It tends to weight slightly more average weight than the green sea turtle, and reaches more massive top sizes. The Loggerhead sea turtle (Caretta caretta) reaches a maximum size of  and weight of , while the Green sea turtle (Chelonia mydas) reaches a maximum weight in the range of . The Flatback sea turtle (Natator depressus) may reach a weight of up to . Other species of Sea turtles are small-medium in size, but are still considered as large-sized for a typical turtle.

 The largest extant freshwater turtle is possibly the North American alligator snapping turtle (Macrochelys temminckii), which has an unverified maximum reported weight of , although this is challenged by several rare, giant softshell turtle from Asia (Rafetus and Pelochelys) unverified to  and nearly  in total length. The Yangtze giant softshell turtle (Rafetus swinhoei), a critically endangered species of softshell turtle, is sometimes considered as the largest extant freshwater turtle. The heaviest recorded specimen was reported to weigh . Some researchers have claimed that a related species, the Asian giant softshell turtle (Pelochelys cantorii), is the largest living species of freshwater turtle. However, such claims are fraught with problems, because it now seems likely that this species is actually a composite, i.e., consisting of several separate, presently undifferentiated species that have all been traditionally but erroneously lumped together taxonomically as a single species. In the genus chitra, two species of critically endangered turtles have been reported to grow to massive sizes. The Asian narrow-headed softshell turtle (Chitra chitra), at up to , and the Indian narrow-headed softshell turtle (Chitra indica), at up to , are also contenders for the title of the largest extant freshwater turtle.

 The Galápagos tortoise (Chelonoidis nigra) and the Aldabra giant tortoise (Aldabrachelys gigantea) are considered the largest truly terrestrial reptiles alive today. While the Aldabra tortoise averages larger at , the more variable-sized Galapagos tortoise can reach a greater maximum size of  and  in total length. The Aldabra giant tortoise has a maximum recorded weight of . The African spurred tortoise (Centrochelys sulcata) is the third-largest extant tortoise (and the largest mainland tortoise) in the world. The large adults of this species may reach  in length and weigh more than . Other relatively large-sized tortoises include the Yellow-footed tortoise (Chelonoidis denticulatus) and Leopard tortoise (Stigmochelys pardelis), at up to , and the Asian forest tortoise (Manouria emys), at up to  or more, can be rather large as well. The tortoise Megalochelys, of the Pleistocene epoch from what is now Pakistan and India, was even larger, at nearly  in shell length and .

The largest of side-necked turtles (Pleurodira) is the Arrau turtle (Podocnemis expansa). Its carapace length is up to  and adults can reach up to  in weight. There are also reports of these turtles weighing up to . The Mata mata (Chelus fimbriata) is another large species of side-necked turtle with a carapace length of up to  and weight of more than .

There are many extinct turtles that vie for the title of the largest ever. The largest freshwater turtle seems to be Stupendemys, with an estimated parasagittal carapace length of  and weight of up to . A close contender is Archelon ischyros, a sea turtle, which reached a length of  and a weight of .

Meiolaniformes 
A terrestrial relative of turtles survived until about 2,000 years ago, the Australasian Meiolania at about  long and a weight of over . Later research suggests the maximum length possibly over .

Plesiosaurs (Plesiosauria) 

Plesiosaurs were aquatic reptiles of the Mesozoic era. They had a broad flat body, a short tail, and strong flippers. Most of the Plesiosauroidea group are identified by their long necks, while Pliosauroidea are usually short-necked. The largest known plesiosauroid is Aristonectes, with a body length of  and body mass of  or even . The largest well known pliosauroid is Pliosaurus funkei at  in length.

Crocodilians (Crocodilia) 

Some species of crocodiles such as Saltwater crocodile (Crocodylus porosus), Nile crocodile (Crocodylus niloticus), American crocodile (Crocodylus acutus) and the critically endangered Orinoco crocodile (Crocodylus intermedius) can reach lengths of  or more. The largest known specimen among the living crocodilians was an Orinoco crocodile with a length of  . One of the largest known Saltwater crocodile measured  and was shot in Papua New Guinea. A  long individual was captured alive in Mindanao in 2011. The largest confirmed Saltwater crocodile on record was  long, and weighed about . In 2006, Guinness World Records accepted claims of a ,  male saltwater crocodile, living within Bhitarkanika National Park. Due to the difficulty of trapping and measuring a large living crocodile, the accuracy of these dimensions is yet to be verified. These observations and estimations have been made by park officials over the course of ten years, from 2006 to 2016, however, regardless of the skill of the observers it cannot be compared to a verified tape measurement, especially considering the uncertainty inherent in visual size estimation in the wild. The largest Nile crocodile accurately measured, shot near Mwanza, Tanzania, measured  and weighed about . Another large Nile crocodile specimen was purported to be a man-eater from Burundi named Gustave; it was thought to have been more than  long. The American crocodile is also one of the largest crocodile species, with large males in the southern part of their range reported to approach  in size. Based on projections from various skulls, the largest males may have reached  in length, and their predicted mass reached up to . Other crocodiles can also grow to large sizes, such the Mugger crocodile, which typically reaches an average maximum length of , and has a maximum reported length of . The extinct Crocodylus thorbjarnarsoni was the largest species in its genus, growing up to  in length. The largest true crocodile ever existed is Euthecodon which estimated to have reached  or even  long.

A  long gharial was killed in the Ghaghara River in Faizabad in August 1920. Male gharials may grow up to a length of . The heaviest recorded gharial was a male measuring  in total length and weighing . The False gharial is also a large crocodilian with males reaching  in length, weighing up to at least . The largest gavialid to ever exist was the extinct Rhamphosuchus from the Miocene of Asia. It was originally thought to be  long and more than  in weight but later estimations suggest  and . Based on its fossils, the latter species was less massive and heavy than the other giant crocodilians, weighing an estimated .

The largest member of the family Alligatoridae is the Black caiman (Melanosuchus niger) with the American alligator (Alligator mississippiensis) sometimes growing to similar lengths. Black caimans can reach more than  in length and weigh up to . American alligators can be almost as large, with males reaching  in length and weighing over . Unverified reports suggest lengths of up to  for the black caiman and  for the American alligator, reaching weights of over , but such lengths are probably exaggerated.
 
The giant prehistoric caiman, Purussaurus, from northern South America during the Miocene epoch grew up to  long and could weigh up to 8 tonnes, making it one of the largest crocodilians ever. Other contenders for the largest crocodilian ever include the late Cretaceous period Deinosuchus, at up to  and . Relative of crocodilians, Sarcosuchus imperator of the early Cretaceous was found in the Sahara desert and could measure up to  and weigh an estimated .

Pterosaurs (Pterosauria) 

A Mesozoic reptile is believed to have been the largest flying animal that ever existed: the pterosaur Quetzalcoatlus northropi, from North America during the late Cretaceous. This species is believed to have weighed up to , measured  in total length (including a neck length of over ) and measured up to  across the wings. Another possible contender for the largest pterosaur is Hatzegopteryx, which is estimated to have had an  wingspan. An unnamed Mongolian pterodactyloid pterosaur and Arambourgiania from Jordan could reach a wingspan of nearly .

Non-avian dinosaurs (Dinosauria) 

 The main contender for the longest sauropod and the longest known vertebrate is Maraapunisaurus fragillimus. Known only by lost vertebra, it was estimated at  in length and  in weight but later studies suggest smaller size, about  in length and  in weight. Breviparopus taghbaloutensis was mentioned in The Guinness Book of Records as the longest dinosaur at  but this animal is known only from fossil tracks. The better studied Supersaurus was possibly as long as over . One of the heaviest sauropods was Argentinosaurus at  in length and  or even  in body mass. The tallest sauropods were probably Xinjiangtitan and Sauroposeidon with total height of  and , respectively.
 The largest non-avian theropod was Tyrannosaurus Rex, estimated at  in length and around  in weight.
 The largest thyreophoran was Ankylosaurus at  in length and  in weight.
 The largest ceratopsian was Triceratops, reaching  in length and  in weight.
 The largest ornithopod was the Late Cretaceous Shantungosaurus at up to , and  in length.

References

Notes

Lists of reptiles
Reptiles