Of all the stars of the American screen, only Lillian Gish has had a longer career than Mickey mouse. The eternally cheerful rodent, Walt Disney's first major cartoon character, made his movie debut 60 years ago - Nov. 18, 1928 - at New York's Colony Theater in "Steamboat Willie."

As Disney recalled in 1934, Mickey Mouse was born on a train ride from New York to Los Angeles. "The idea completely engulfed me," the cartoonist wrote. "The wheels turned to the tune of it. `Chug, chug, mouse, chug, chug, mouse,' the train seemed to say. The whistle screeched it. `A m-m-mowa-ouse,' it wailed."Disney wanted to call his creation Mortimer. His wife or somebody else - no one knows for sure - insisted on Mickey. Furthermore, Disney himself never could draw Mickey Mouse. The "dream mouse in a pair of red velvet pants with two huge pearl buttons" was designed and rendered by Ub Iwerks, who received "drawn by" credits on the first cartoons and comic strips.

It hardly mattered. Disney's genius was more entrepreneurial than artistic, and Mickey Mouse provided the seed money for more ambitious proj-ects. "Flowers and Trees" (1932) used the Technicolor process for the first time in the animated field. "Snow White and the Seven Dwarfs" (1937) was the first full-length animated feature.

Although Donald Duck had a greater following among the moviegoing public, Disney always remained partial to Mickey. He once described a Mickey Mouse film audience as "parts of people . . . that deathless, ageless, absolutely primitive remnant of something in every world-wracked human being which makes us play with children's toys and laugh without self-consciousness at silly things, and sing in bathtubs, and dream and believe that our babies are uniquely beautiful. You know, the Mickey in us."

Today, more than 20 years after Disney's death, the executives of the movie studio that still bears his name obviously have less affection for Mickey. The character has been largely relegated to duty at the Disney entertainment parks in Anaheim, Calif., and Orlando, Fla.

Indeed, the studio has prospered in recent years by concentrating on feature films starring live actors, including "Down and Out in Beverly Hills, "Outrageous Fortune" and "The Color of Money." These and other hits have made the Walt Disney Co. one of Hollywood's Big Three, along with Paramount and Warner.

But Disney executives have by no means forgotten the studio's roots. The top-grossing Disney film of 1988 has been "Who Framed Roger Rabbit," a path-breaking comedy-mystery with animated and live characters. Because of its $40 million cost and novel concept, "Roger Rabbit" was regarded as an iffy prospect at the box office.

However, the movie made a bundle for Disney - and made Roger the studio's latest cartoon superstar. Plans are now afoot to have Roger join Mickey, Donald, Pluto and the gang as a regular attraction at Disneyland and Disney World.