Leslie James Clark (November 17, 1907 – September 12, 1979) was an American animator and the first of Disney's Nine Old Men, joining Walt Disney Productions in 1927.

Les Clark was born in Ogden, Utah in 1907, the eldest of 12 children to James Clark, a carpenter, and Lute Wadsworth. By 1910, the family lived in Salt Lake City and by 1920, they lived in Twin Falls, Idaho. By 1930, they lived in Los Angeles, where Clark attended Venice High School. During high school, he worked a summer job at an ice cream shop near the Walt Disney Studio. Walt and Roy Disney were frequent patrons at the shop, and Walt had once complimented Les on his lettering job of the menus. Eventually, Clark asked Walt for a job. He recalled Walt's reply:

...[Walt said] 'Bring some of your drawings in and let's see what they look like.' So, I copied some cartoons and showed them to Walt. He said I had a good line, and why don't I come to work on Monday.

In 1927, Clark began working the Monday after he graduated high school for a temporary position, first as a camera operator and later as an ink and paint artist. At the time, the studio were finishing the Alice Comedies and starting work on Oswald the Lucky Rabbit. In 1928, Disney traveled to New York to renegotiate their contract with Charles Mintz. Disney refused to accept a less acceptable contract leaving the character to Mintz, who held the character's copyrights. On the way back to Los Angeles, Disney and Ub Iwerks co-created Mickey Mouse as a replacement. Iwerks mainly animated the first Mickey Mouse cartoons Plane Crazy (1928), The Gallopin' Gaucho (1928), and Steamboat Willie (1928) in which Clark worked as an inbetweener. A year later, Clark made his debut as an animator for the first Silly Symphony short The Skeleton Dance (1929). He drew the scene of a skeleton playing on another skeleton's ribcage like a xylophone.

In 1930, Iwerks left Disney to form his namesake studio. Clark then became the official animator for Mickey Mouse. Most notably, Clark animated the character in the 1935 short The Band Concert. On the Silly Symphony short The Goddess of Spring (1934), Clark used his sister Marceil as a reference model for the character Persephone. After watching his finalized animation, Clark remembered: "I was very disappointed in my effort and I told Walt so."

On Snow White and the Seven Dwarfs (1937), Clark animated several scenes of the dwarfs during the "Silly Song" sequence, including Dopey smashing his face with a cymbal, Doc playing a horn, and Doc and Happy running from Sneezy's loud sneeze. He also animated the scene of the three dwarfs dancing with Snow White, a moment first filmed in live-action that used as a visual reference for the animators. Clark then animated Mickey Mouse in The Sorcerer's Apprentice segment for Fantasia (1940). Clark animated the scenes in which Mickey "puts the hat on and starts bringing the brooms to life—the dance up the stairs and the water vats—until he exits over the water." Clark also animated the Sugar Plum Fairies for The Nutcracker Suite segment.

Meanwhile, Clark animated a few scenes of the title character in Pinocchio (1940), most particularly when Pinocchio turns around when Geppetto inspects him before leaving for school. He next animated the train sequence to Baia in The Three Caballeros (1945). Andreas Deja complimented Clark's animation, writing it is "charming, as it chugs along to an energetic musical beat through a landscape that is reminiscent of a children's illustration."

For Song of the South (1946), Clark handled the animation interacting with Uncle Remus (portrayed by James Baskett) during the "Zip-a-Dee-Doo-Dah" musical number. A year later, he animated the Singing Harp for the Mickey and the Beanstalk segment in Fun and Fancy Free (1947). Melody Time (1948) soon followed, in which Clark animated the bumblebee for the Bumble Boogie segment.