Clarence Charles "Ducky" Nash (December 7, 1904 – February 20, 1985) was an American voice actor and impressionist. He is best remembered as the original voice of the Disney cartoon character Donald Duck. He was born in the rural community of Watonga, Oklahoma, and a street in that town is named in his honor. In 1993, he was posthumously made a Disney Legend for his contributions to Walt Disney films.

Nash made a name for himself in the late 1920s as an impressionist for KHJ, a Los Angeles radio station, on their show, The Merrymakers. He later was employed by the Adohr Milk Company for publicity purposes. Dubbed "Whistling Clarence, the Adohr Bird Man", Nash rode the streets with a team of miniature horses and gave treats to the children. In 1932, Nash happened by the Disney Studio with his team of horses, and decided to leave a copy of his Adohr publicity sheet with the receptionist. As it turns out, his name was recognized from a reprise appearance on The Merrymakers a few days previous, and Walt Disney had been impressed by Nash's vocal skills. He was asked to make an informal audition.

One source indicates Nash auditioned before a casting director for Walt Disney Studios and did a voice impression of a billy goat that Nash had started doing as a child in Watonga. The director then reached for the intercom and told Walt Disney, "I think we have found our duck." Another version indicates Nash went through several of his voices, and Walt Disney happened by when Nash gave his impersonation of a family of ducks. Disney declared Nash perfect for the role of a talking duck in their upcoming animated short, The Wise Little Hen. The duck was Donald Duck, who Nash went on to voice for 51 years, in over 120 shorts and films. The last film to feature Nash's famous voice was 1983's Mickey's Christmas Carol, although he continued to provide Donald's voice for commercials, promos, and other miscellaneous material until his death.

As early as 1938, promoters from lecture circuits were approaching him on his unique voice of Donald. Disney reportedly did not like the engagements at first, feeling that a human doing the voice would be spoiling the illusion, but then long after he had second thoughts. In early 1941, Nash was traveling on personal appearance tours sponsored by Disney. During World War II, Nash, with his ventriloquist puppet of Donald, which was built by Disney's character modeling department, became a regular performer at USO bond rallies and other events to support the war effort. In the mid-1940s, Roy and Walt approved the Donald puppet and they decided to harness it for the 1944 re-release of Snow White and the Seven Dwarfs. RKO and Disney were unsure how the film would do the second time around at the box office after its initial blockbuster run, so they did a promotional campaign with Disney characters including Nash performing with the Donald puppet. During the promotional period of Fun and Fancy Free, he did multiple radio appearances from May to September 1947, with one of those appearances starring Disney himself. He voiced Donald for 1950s TV commercials.

Nash's Donald Duck voice was achieved by what is called buccal speech: an alaryngeal form of vocalization which uses the inner cheek to produce sound rather than the larynx. He first discovered it while trying to mimic his pet goat Mary. In his days before Disney, Nash performed in vaudeville shows where he often spoke in a "nervous baby goat" voice.

Donald Duck became one of the world's most famous cartoon characters, in great part due to Nash's voice. The voice is distinctive both for its ducklike quality and the fact that it is often very difficult for anybody to understand, especially when Donald flew into a rage (which happened fairly often). To keep Donald's voice consistent throughout the world, Nash voiced the character in all foreign languages the Disney shorts were translated to (with the aid of the phonetic alphabet), meaning Donald retained his same level of incoherency all across the globe.

In addition to Donald's voice, Clarence Nash also voiced Donald's nephews Huey, Dewey and Louie and his girlfriend Daisy in Mr. Duck Steps Out, and Mickey Mouse in The Dognapper. He provided the meows and yowls of Figaro the kitten and some donkey brays in Pinocchio and in a handful of shorts. He also did the whistling (Nash was a great whistler, hence his nickname "Whistling Clarence") of birds in Snow White and the Seven Dwarfs and Cinderella, voiced a bullfrog in Bambi and Mr. Bluebird in Song of the South, did some dog sounds in One Hundred and One Dalmatians and background bird sounds in Enchanted Tiki Room, and voiced Jiminy Cricket for a brief period of time after Cliff Edwards's death in 1971.

Nash's iconic Donald Duck voice would be impersonated elsewhere in animation, most notably in the Tom and Jerry cartoons directed by William Hanna and Joseph Barbera with the character Little Quacker (voiced by Red Coffey) and Hanna-Barbera's Yakky Doodle (voiced by Jimmy Weldon), while Harry E. Lang did Donald Duck-like voices in cartoons at MGM Cartoons and Columbia Pictures, including Tom Cat in the early shorts whenever he hisses. As with most Hanna-Barbera productions, these characters used celebrity impersonations, in these cases an impersonation of Clarence Nash's Donald Duck voice. Because both were much similar to Nash's voice they were often mistakenly attributed to Nash. Likewise, contrary to popular belief, he did not perform the duck voice for Rick Dees' "Disco Duck", which was done by one of Dees' acquaintances. Nash would also use his duck voice on The Burns & Allen Show during the 1940s, playing Gracie's pet duck Herman.