From: He debuted in Alice Solves the Puzzle, released in February of 1925. He reappeared in several cartoons of the Alice's Comedies series. He was then transferred to Oswald the Lucky Rabbit in September of 1927, debuting in The Ocean Hop, where he competes with Oswald in a competition to cross the Atlantic in an aircraft. While continuing to appear (in his original 1925 design) in the Oswald shorts, a redesigned version of the character was introduced in 1927 in the second Mickey Mouse short, The Galloping Gaucho; the Disney crew originally called this version Terrible Tom, but by 1930 it had become clear that he was so similar to the old villain that a new name wasn't really warranted. Pete appeared in countless media ever since, notably in the Donald Duck cartoons, in Disney comics, in House of Mouse and in the feature him Mickey, Donald and Goofy: The Three Musketeers as Captain Pete.
Description: Pete is rather tricky, because his role is seldom the same (though in the comics, he has eventually settled as a thief). Thief, pirate, smuggler, spy, abusive boss or even policeman, Pete has the part of any and all antagonist in the Donald and Mickey shorts.
In 1925, he was introduced as a notorious bootleg (this was the Prohibition era) and "collector of rare crossword puzzles". He was a large bear with a peg-leg. At the end of the short, he was captured by the authorities. Throughout the later Alice and Oswald shorts, Pete, free once again, holds a slightly different part, albeit one that is consistent with his earlier portrayal, as the local cheating tough guy, who never openly does anything illegal enough to attract attention from the police but will antagonize the hero at every turn as well as he can.
Review: Pete is more of an archetype than he is a character (much like Scapin or Figaro, for instance), and thus is not necessarily a very good villain. His central characteristic is that he is a "tough guy", relying on brute strength to get what he wants, with limited intelligence. This makes for a good antagonist figure, but not for an interesting character, I'm afraid; Pete's value is not intrinsic, but depends either on how the writers or animators will exploit his stupidity for gags, or on the threat he poses to the heroes (be it Alice and Julius, Donald, Mickey or anyone else). On the other hand, he's such a simple archetype that every work he's in and every time period will find a good use for him, making him a surprisingly enduring creation. (Note: Captain Pete from The Three Musketeers has a rather different characterization and background, and will be reviewed on his own later).