Left: An animation cel of Oswald the Lucky Rabbit.

Not all of Walt Disney's cartoon creations have achieved the immortality of Mickey Mouse. Disney introduced Mickey in 1927, and by the time of "Steamboat Willie" (1928), the first sound animated cartoon, the mouse's popularity was ensured.

But what of the many other characters who made appearances in Disney cartoons, only to be relegated to the forgotten districts of Toontown?

By CBSNews.com senior producer David Morgan

The first of a series of hybrid live action/animated shorts inspired by Lewis Carroll, "Alice's Wonderland" (produced by Disney in 1923 at a Kansas City, Mo., studio, using the "Laugh-O-Gram Process") featured actress Virginia Davis entering the dreamscape Cartoonland, where trains do loop-the-loops, talking dogs in top hats make up a reception committee, and slobbering lions chase her down a rabbit hole.

Over the next four years 57 Alice Comedies were shot, many of them now lost.  A handful have been released on DVD. 

In 1927 Walt Disney and animator Ub Iwerks created Oswald the Lucky Rabbit as part of a distribution deal with Universal Pictures for an animated cartoon series. The first Oswald cartoon released was "Trolley Trouble," and the rabbit went on to star in 25 more films - several are lost - before Disney had a falling out with Universal over profits. The two parties parted ways.

Oswald continued to appear in films for Universal into the mid-'40s (some animated by Tex Avery), but his star was soon eclipsed by the character Disney created to replace Oswald: Mickey Mouse.

Oswald recently returned to the screen with a guest appearance in the new Disney short, "Get a Horse!" and in the game, "Epic Mickey." 

Ortensia was featured as Oswald the Rabbit's girlfriend in six shorts produced between 1927 and 1928, three of which are lost.  In "Rival Romeos" (left), she's actually fought over by Oswald and Pete, a cat - the Disney universe was nothing if not diverse!.

Ortensia returned in the computer game Epic Mickey, with an upgrade in status - she's now the mother of Oswald's 420 kids – but she still gets no respect, being turned into a statue. 

An alcoholic race horse?  In "The Steeple Chase" (1933), Thunderbolt (in his first and only appearance) is a prize horse whose big race is jeopardized after he meets up with a jug of moonshine. His jockey, Mickey Mouse, is forced to get two stable hands in a pantomime horse costume to take Thunderbolt's place. 

Peter Pig made two film appearances, as a lazybones who refuses to help a neighbor plant corn in "The Wise Little Hen" (1934), which was also the debut of Donald Duck; and as a musician in Mickey Mouse's band, in "The Band Concert" (1935). 

The 1942 omnibus, "Saludos Amigos," produced as a sort of good will tour of South America, included cartoon segments featuring Donald Duck, Goofy, singing parrots - and Pedro, a Chilean mail plane who carries his mail bags in a dangerous flight over the Andes. 

The Brazilian parrot Jose Carioca, also featured in "Saludos Amigos," returned in Disney's follow-up cartoon, "The Three Caballeros" (joining Donald and a rooster from Mexico named Panchito Pistoles).  But Pedro the mail plane dipped out of sight, with nary a cameo in the Disney/Pixar "Planes."

Yes, Mickey's dog Pluto had a son, the puppy star of "Pluto, Jr." (1942), who gets into various mayhem, requiring proud poppa to come to the rescue. 

Despite his obvious cuteness, the little tyke never made another film appearance (nor, by the way, is there any mention of whom the puppy's mother is), though in 1946 Pluto's sibling, K.B., starred in another one-off, "Pluto's Kid Brother." 

Disney never completed a planned WWII cartoon adapted from a Roald Dahl children's book, "The Gremlins," about troublesome creatures with an affinity for tearing apart airplanes in mid-flight. The story was inspired by tales told among RAF pilots. The project was halted over rights issues. (Meanwhile, Bugs Bunny got into a scrape with his own gremlin in the classic, "Falling Hare," which was followed by another Warner Brothers cartoon, "Russian Rhapsody," about "gremlins from the Kremlin" attacking Hitler.)

The tiny saboteurs did appear in Disney comic books in the 1940s, and the Roald Dahl book was republished by Dark Horse Comics in 2006. 

"If you tell 'em a lie, don’t tell a little one, tell a BIG one."  So says Foxy Loxy in this 1943 World War II propaganda short, "Chicken Little," about a fox armed with a psychology book trying to sway poultry into becoming his unsuspecting dinner. Chicken Little is his target ("He looks nice and stupid!"), and a conk on the head leads the bird to spread rumors that the sky is falling.  The story has a decidedly dark ending (for avian life, at least). 

This music teacher character was featured in two Disney shorts, "Melody" (1953), and the Oscar-winning "Toot, Whistle, Plunk and Boom" (1954).

The projected "Adventures in Music" series did not pan out, and Professor Owl made only a couple of stock footage appearances on Disney home video releases introducing other, better known characters. 

Just as home video and DVD releases have brought some forgotten characters back to the fore, so have Playstation and the XBox. The games "Epic Mickey" and "Epic Mickey 2" feature cameos by several past Disney characters, including Oswald the Lucky Rabbit.  No hard feelings?

For more info: 

cartoonresearch.com
traditionalanimation.com
"The Gremlins" by Roald Dahl (Dark Horse Comics)
"Alice's Wonderland" at the Internet Archive
Discarded Disney (blog)
Mouse Planet