Sylvester Shyster is a recurring villain from the Mickey Mouse comics. He is a crooked lawyer and con man who often works with Pete. The character has been described by some as a weasel or a rat (the latter being Gottfredson's own interpretation), but his ears suggest that he is rather an anthropomorphic canine.
He first appeared in the comic strip adventure "Mickey Mouse in Death Valley", the first real Mickey Mouse continuity, which was partially written by Walt Disney and drawn by Win Smith and other artists, before being taken over by Floyd Gottfredson (plot and art). In this story, Sylvester Shyster was a crooked lawyer who attempted, with the help of his henchman Pete, to deprive Minnie Mouse of her inheritance.
Shyster and Pete have been causing trouble for Mickey and his friends since then. Shyster is generally depicted as the duo's brain, with Pete acting as the brawn. He is probably the only person Pete will listen to without rebellion.
After Shyster's first appearance, Gottfredson made no further references to his profession as a lawyer, apart from his name; one might theorize, though it is not canon, that Shyster was disbarred due to his arrest and imprisonment at the end of "Mickey Mouse in Death Valley." Later creators occasionally referenced Shyster's role as a lawyer, with one story ("Trial and Error," 2007) forcing Shyster to defend Mickey himself in an overseas courtroom.
Shyster disappeared for a time after 1934, but made comebacks in 1942, 1950, and again in various 1960s Italian-created stories. More recently, publisher Egmont Creative A/S (in Denmark) revived Shyster as a regular character, a capacity in which he continues today.
In "Race to the South Seas" (March of Comics #41, 1949), a Donald Duck story by Carl Barks, a variant of Shyster appeared as Scrooge McDuck's lawyer, but his appearance differed from that in the Mickey Mouse strip and he was not depicted as a villain in that story.