Question: What Disney cartoon character first drawn by Iwerks stared in the animated short film "The Nifty Nineties"?

Context articles: Truant Officer Donald
Walt Disney's Classic Cartoon Favorites
Steamboat Willie
The Nifty Nineties
Sleigh Bells (film)
Minnie Mouse
Riley Thomson
Just Mickey
Crazy Castle (series)
Plane Crazy

Truant Officer Donald is an animated short film produced in Technicolor by Walt Disney Productions and released to theaters on August 1, 1941 by RKO Radio Pictures.
 The film was nominated for an Academy Award for Best Animated Short Film in 1942 but lost to another Disney cartoon "Lend a Paw".
 The story features Donald Duck working as a truant officer and making sure that Huey, Dewey and Louie go to school.
 The film was directed by Jack King while Clarence Nash provided the voices of Donald and the nephews.
Walt Disney's Classic Cartoon Favorites is a series of DVDs by Walt Disney Home Video.
 Each release would feature around one hour of "Disney" animated short films, grouped by a starring character or a theme.
 It is based on the original Walt Disney Cartoon Classics line of videotapes of the 1980s.
 As opposed to the chronological nature of the "Walt Disney Treasures" line, each release would feature various cartoons in no particular order.
 The series featured a total of four waves of releases, between January 11, 2005 and April 11, 2006.
 Another very similar line was "Walt Disney's Funny Factory".
Steamboat Willie is a 1928 American animated short film directed by Walt Disney and Ub Iwerks.
 It was produced in black-and-white by Walt Disney Studios and was released by Celebrity Productions.
 The cartoon is considered the debut of Mickey Mouse and his girlfriend Minnie, although both the characters appeared several months earlier in a test screening of "Plane Crazy".
 "Steamboat Willie" was the third of Mickey's films to be produced, but was the first to be distributed because Walt Disney, having seen "The Jazz Singer", had committed himself to producing the first fully synchronized sound cartoon.
The Nifty Nineties is an animated short film produced in Technicolor by Walt Disney Productions and released to theaters on June 20, 1941 by RKO Radio Pictures.
 the animated short was directed by Riley Thomson and animated by Ward Kimball, Walt Kelly, Fred Moore, Claude Smith, David Swift, and Les Clark with effects animation by Art Fitzpatrick.
 The film stars Mickey and Minnie Mouse and romanticizes the decade of the 1890s.
Sleigh Bells is an American animated short film featuring Oswald the Lucky Rabbit.
 It was directed by Walt Disney and Ub Iwerks, and released in 1928 by The Walt Disney Studio.
 The film was thought to be lost until a print was discovered in the BFI National Archives in 2015, the film was for two years the last extant Oswald cartoon directed by Walt Disney; until 2017, when "High Up", the last Oswald cartoon made by Disney, was rediscovered.
Minnie Mouse is a funny animal cartoon character created by Ub Iwerks and Walt Disney.
 She and Mickey Mouse were first drawn by Iwerks in 1928.
 The comic strip story "The Gleam" (published January 19–May 2, 1942) by Merrill De Maris and Floyd Gottfredson first gave her full name as Minerva Mouse, although this is seldom used.
Riley A. Thomson, Jr. (October 5, 1912 – January 26, 1960) was an American animator and comics artist who spent most of his career working with Walt Disney films and characters.
 He directed six Disney short films including "The Nifty Nineties" and "Symphony Hour".
Just Mickey (alternately titled Fiddlin' Around) is a 1930 animated short film produced by Walt Disney Productions and released by Columbia Pictures.
 The film shows Mickey Mouse playing a violin on stage as a one-person show; as indicated by the title, Mickey is the only character to appear in the film.
 It was directed by Walt Disney and is the first Mickey cartoon not animated by Ub Iwerks.
The "Crazy Castle" series is an action-puzzle game series created by Kemco and released on the Famicom Disk System, NES, Game Boy, Game Boy Color and Game Boy Advance.
 It stars different popular cartoon characters, most notably the Warner Bros. cartoon character, Bugs Bunny, and the Walt Disney cartoon character, Mickey Mouse.
Plane Crazy is an American animated short film directed by Walt Disney and Ub Iwerks.
 The cartoon, released in 1929 by the Walt Disney Studios, was the first creation of the character Mickey Mouse.
 It was made as a silent film and given a test screening to a theater audience on May 15, 1928, but failed to pick up a distributor.
 Later that year, Disney released Mickey's first sound cartoon, "Steamboat Willie", which was an enormous success.
 Following this, "Plane Crazy" was released as a sound cartoon on March 17, 1929.
 It was the fourth Mickey film to be released after "Steamboat Willie", "The Gallopin' Gaucho", and "The Barn Dance" (1928).