Werewolf by Night director <PERSON> describes some of the monster heads in the IGN video, Werewolf by Night: Monster Easter Eggs and Director's Sequel Hopes:
https://www.youtube.com/watch?v=sdWgAs2wRno
Sasquatch / Bigfoot
The Sasquatch family are a group of humanoid beasts hiding in the forests of British Columbia. Humans call their species Sasquatch or Bigfoot.
- https://marvel.fandom.com/wiki/Sasquatch_(Race)
The race of reclusive, forest-dwelling behemoths was adapted to Marvel Comics by <PERSON> & <PERSON> in their 2nd volume of Alpha Flight (1997).
- https://twitter.com/MaximilanMarvel/status/1578315247953534976
Sasquatches first appeared in the 1997 reboot of Alpha Flight (mistaken for the human mutate Sasquatch, <PERSON>).
The MCU Sasquatch is similarly Canadian (British Columbian).
- https://twitter.com/MaximilanMarvel/status/1578469260086517760
Screencap of <PERSON> fighting a <PERSON> illustration:
<PERSON>
- https://marvel.fandom.com/wiki/Krogg_(Demon)_(Earth-616)
First Appearance: Werewolf by Night I#8 (August, 1973)
[...]
History:
(Werewolf by Night I#8 (fb)) - Several centuries ago, the warlock <PERSON> summoned <PERSON> to be his servant, but <PERSON> refused to obey him and instead terrorized the area, devouring those humans it chanced upon. <PERSON> was able to trap the demon in a cave in the California foothills but eventually died guarding the prison.
(Werewolf by Night I#8) - <PERSON> stumbled across the hidden cave, finding a rabbit, and broke through the door he found there and from where he had heard moaning. Invisible, <PERSON> was able to escape and that night came across <PERSON> in his werewolf form, recognizing his scent and offered to kill him swiftly as an act of mercy. [...]
- http://www.marvunapp.com/Appendix5/kroggwbn.htm
Screencap of <PERSON> fighting <PERSON> illustration:
Two-Headed Mermaid
Could be based on one of these two creatures from the comics: Mermaids, or Sirenas (Filipino mythology). 715
The non-human-looking faces and heads of the Two-Headed Mermaid are more akin to the Sirena than the usual mermaid.
- https://marvel.fandom.com/wiki/Sirenas
Screencap of Mermaid/Sirena illustration:
Dr. Glitternight-summoned bat creature
[...] the bat-like creature mounted in the Bloodstone Manor was based on the bat creatures summoned by Dr. <PERSON> in Werewolf By Night #28 (1975), created by <PERSON> & <PERSON>!
- https://twitter.com/MaximilanMarvel/status/1579294101874544645
Vampire
Vampires! Or, more specifically, the #Nosferati sect of vampires, led by the one known as #Nosferatu! Adapted to Marvel Comics by <PERSON>, <PERSON> & <PERSON> in Bloodstone #3 (2001), the series that introduced #ElsaBloodstone to the Marvel Universe!
WerewolfByNight
- https://twitter.com/MaximilanMarvel/status/1578326402776301569
History: (Bloodstone#4 (fb) - BTS) - Ten thousand years ago Lord <PERSON> became a vampire.
At an unknown point in his life Lord <PERSON> became an adversary of <PERSON>.
In the 1930's Lord <PERSON> and his forces were defeated by <PERSON> in a struggle the Lord described as an "airship debacle". Lord <PERSON> survived this battle unlike most of his forces. [...]
- http://www.marvunapp.com/Appendix3/nosferatuvamp.htm
Screencap of Nosferati vampire illustration:
The following monster heads weren't mentioned by <PERSON> in the above IGN video:
Reptilian Monster
Monster that looks like an Oni (Japanese mythology) 786