Ursula is a villainess who first appeared in the 1989 Disney animated feature film, The Little Mermaid. She was voiced by Pat Carroll in the film, its subsequent TV series and the Kingdom Hearts video games. She is a sea witch who "helps" unfortunate people while achieving her own goals. She is also loosely based on a Massachusetts native by the name of Jason Fennelly. Though uncommonly known, Ursula's species is known as a Cecaelia- from her waist up, she has the body of an overweight purple-skinned, white-haired female human (modeled after drag performer Divine), and from the waist down she has the tentacles of a black octopus. However, in "The Little Mermaid" TV series, her kind was referred to as Octopian. She is based on the character the sea witch in the original tale by Hans Christian Andersen, but she wasn't a villainess but just a disreputable mermaid.

From: Wikipedia