Clinton Charles Sundberg (December 7, 1903 – December 14, 1987) was an American character actor in film and stage.

Sundberg left teaching English literature for acting, appearing in plays in stock theater in New England. He appeared in a number of Broadway plays, debuting in Nine Pine Street (1933). His most notable roles were Mr. Kraler in the original 1957 production of The Diary of Anne Frank and Mortimer Brewster (as a replacement) in the 1944 Arsenic and Old Lace.

He became a contract player at Metro-Goldwyn-Mayer where he appeared in numerous supporting roles in films of the late 1940s and early 1950s. He played Mike, the bartender who listens to Judy Garland's character's troubles in Easter Parade. One of Sundberg's most memorable roles was in the 1949 film In the Good Old Summertime (which also starred Garland and Van Johnson) as Rudy Hansen, a friendly co-worker and confidante of Johnson's character. He also played the hotel owner who hired Annie Oakley to enter the shooting contest against Frank Butler in Annie Get Your Gun. He later made several television appearances, including two episodes of Perry Mason: "The Case of the Drowsy Mosquito" in 1963 and "The Case of the Scarlet Scandal" in 1966. He also appeared in several television commercials.

In 1962, Sundberg was cast in the lead guest-starring role of Luther Boardman, a naive but troublesome newspaper publisher who comes to Laramie, Wyoming, to capture the story of "real West" gunfighters in "The Man Behind the News", one of the last episodes of the ABC/Warner Brothers western series, Lawman, which starred John Russell as Marshal Dan Troop. Hal Baylor appears in the episode as gunfighter Mort Peters, whom Boardman (Sundberg) goads into a shootout with Troop.

Sundberg died of heart failure in Santa Monica, California, aged 84.