Walt Disney: Directed a lot of his early shorts prior to Gillett and Jackson taking over the duties for him. His last short was "The Golden Touch".
Ub Iwerks: Directed some of the studios early shorts prior to his departure in 1930.
Burt Gillett: A prolific director for Walt's early 30's shorts, only to leave in 1934 for an ill-fated venture at Van Beuren Studios. He would briefly return in the late 30's. His most famous short was "Three Little Pigs."
Hamilton "Ham" Luske
Pinto Colvig: His sole directorial effort was "Mickey's Amatuers".
Walt Pfeiffer: Same as above.
Erdman "Ed" Penner: Same as above.
Clyde "Gerry" Geronimi
Norm Ferguson: Normally an animator, Fergy's sole short subject directing credit was "Pluto's Playmate".
Rudolf Ising: Sole effort was the outsourced short "Merbabies".
Keep Circulating the Tapes: There are still a handful of classic Disney shorts that didn't make their way into the Walt Disney Treasures lineup, including two of Goofy's 60s shorts, Freewayphobia #1 and Goofy's Freeway Troubles ("How to Ride a Horse" and "El Gaucho Goofy" from the 40s aren't counted here, as they was technically part of other features, the former as part of The Reluctant Dragon (and can be found intact on Walt Disney Treasures: Behind the Scenes At Walt Disney Studios) and the latter as part of Saludos Amigos), Chip 'n Dale's three solo shorts (although they are available on VHS and some of them on DVD) and poor little "Susie the Little Blue Coupe" didn't get into the Disney Rarities set (although it has somehow made its way onto public domain DVDs like Bazooka Joes cartoons, as well as included on DVD releases of The Adventures of Ichabod and Mr. Toad and The Love Bug as extras and as part of a series of DVDs called "It's a Small World of Fun"). They have also only released a select few of the early Alice Comedies on the Disney Rarities and Oswald the Lucky Rabbit sets, but many others are available via VCI and Inkwell Images DVD collections. Also, the obscure Disney short about "Menustration" hasn't been officially released, but has fallen into the public domain. Donald is also missing three shorts from the 1960s ("Donald's Fire Survival Plan", "Steel and America" and "Family Planning"), and two '60s oneshots "Scrooge McDuck and Money" and "It's Tough To Be a Bird" have also not received a release.
Old Shame: Director Wilfred Jackson disliked the early Mickey Mouse short "The Castaway", and from it's completion vowed to never again make another picture that didn't feel like a Disney cartoon, according to The Illusion of Life: Disney Animation.