Excalibur
Geoffrey of Monmouth, in his "Historia Regum Britanniae" ("The History of the Kings of Britain", c. 1136), Latinised the name of Arthur's sword as "Caliburnus" (potentially influenced by the Medieval Latin spelling "calibs" of Classical Latin "chalybs", from Greek "chályps" ["χάλυψ"] "steel"). Most Celticists consider Geoffrey's "Caliburnus" to be derivative of a lost Old Welsh text in which "bwlch" (Old Welsh "bulc[h]") had not yet been lenited to "fwlch" (Middle Welsh "vwlch" or "uwlch"). In the late 15th/early 16th-century Middle Cornish play "Beunans Ke", Arthur's sword is called "Calesvol", which is etymologically an exact Middle Cornish cognate of the Welsh "Caledfwlch". It is unclear if the name was borrowed from the Welsh (if so, it must have been an early loan, for phonological reasons), or represents an early, pan-Brittonic traditional name for Arthur's sword.
Mr. Merlin
Merlin hires Zachary Rogers (Clark Brandon) to work in his garage, and when Zac pulls a crowbar out of a bucket of cement, the crowbar is revealed to be Arthur's sword Excalibur and Merlin must reveal himself to Zac and make him an apprentice. Leo Samuels (Jonathan Prince) is Zac's best friend, who naturally has no idea his best buddy is a "wizard in training". Elaine Joyce is Alexandria ("Alex"), Max's equally magical liaison with an unseen "council" (who insisted Merlin take on an apprentice or lose both his powers and immortality).
"Note": A "Mr. Merlin" strip ran briefly in the British "TV Comic".