Monster from Merriam-Webster
an animal of strange or terrifying shape
a mythical monster
a sea monster
English speakers will commonly use the word "monster" for "strange or terrifying" animals or people. And will also use the word for "extra large". "Monsters of the Midway" was once a well-known expression to describe the American football team Chicago Bears and captured both meanings.
Etymology for "monster" from etymonline.com
Abnormal or prodigious animals were regarded as signs or omens of impending evil. Extended by late 14c. to fabulous animals composed of parts of creatures (centaur, griffin, etc.). Meaning "animal of vast size" is from 1520s; sense of "person of inhuman cruelty or wickedness, person regarded with horror because of moral deformity" is from 1550s. As an adjective, "of extraordinary size," from 1837. In Old English, the monster Grendel was an aglæca, a word related to aglæc "calamity, terror, distress, oppression." Monster movie "movie featuring a monster as a leading element," is by 1958 (monster film is from 1941).