Filmography
| Role | Title | Year | Character |
|---|---|---|---|
| Actor | A Bug's Life | 1998 | Mr. Soil |
| Actor | Planet of the Apes | 1968 | Cornelius |
| Actor | Batman (1966) | Bookworm | |
| Actor | Escape from the Planet of the Apes | 1971 | Cornelius |
| Actor | Battle for the Planet of the Apes | 1973 | Caesar |
| Actor | Bedknobs and Broomsticks | 1971 | Mr. Jelk |
| Actor | Conquest of the Planet of the Apes | 1972 | Caesar |
| Actor | Fright Night | 1985 | Peter Vincent |
| Actor | Planet of the Apes | Galen | |
| Actor | Overboard | 1987 | |
| Producer | Overboard | 1987 | |
| Actor | The Longest Day | 1962 | Pvt. Morris |
| Actor | Cleopatra | 1963 | Octavian - Caesar Augustus |
| Actor | The Black Hole | 1979 | V.I.N.CENT (voice) |
| Actor | Evil Under the Sun | 1982 | Rex Brewster |
| Actor | The Poseidon Adventure | 1972 | Acres |
| Actor | Agrios, skliros kai adistaktos | 1975 | Tony Da Vince |
| Actor | Fright Night Part 2 | 1988 | Peter Vincent |
| Actor | That Darn Cat! | 1965 | Gregory Benson |
| Actor | How Green Was My Valley | 1941 | Huw Morgan |
| Actor | The Cat from Outer Space | 1978 | Mr. Stallwood |
| Actor | Lassie Come Home | 1943 | Joe Carraclough |
| Actor | Class of 1984 | 1982 | Terry Corrigan |
| Actor | The Pirates of Dark Water | ||
| Actor | Behind the Planet of the Apes | 1998 | Himself - Hosted by (also archive footage) |
| Actor | The Return of the King | 1980 | Samwise Gamgee |
| Actor | Cutting Class | 1989 | Mr. Dante |
| Actor | The Greatest Story Ever Told | 1965 | Matthew |
| Actor | It! | 1966 | Arthur Pimm |
| Actor | The Legend of Hell House | 1973 | Benjamin Franklin Fischer |
| Actor | Tales of the Gold Monkey | Bon Chance Louie | |
| Actor | Macbeth | 1948 | Malcolm |
| Actor | Funny Lady | 1975 | Bobby Moore |
| Actor | The Martian Chronicles | Father Stone | |
| Actor | The Adventures of Bullwhip Griffin | 1967 | Bullwhip Griffin |
| Actor | Miracle on 34th Street | 1973 | Dr. Sawyer |
| Actor | The Life and Times of Judge Roy Bean | 1972 | Frank Gass |
| Actor | Thunderhead - Son of Flicka | 1945 | Ken McLaughlin |
| Actor | Hey There, It's Yogi Bear | 1964 | Bullwinp Griffin |
| Actor | The Second Jungle Book: Mowgli & Baloo | 1997 | King Murphy |
| Actor | Midnight Lace | 1960 | Malcolm |
| Actor | Alice in Wonderland (1985) | The March Hare | |
| Actor | The Big Picture | 1989 | Judge |
| Actor | The Fantastic Journey | Dr. Jonathan Willoway | |
| Actor | Shakma | 1990 | Sorenson |
| Actor | Carmilla | 1989 | Inspector Amos |
| Actor | Man Hunt | 1941 | Vaner |
| Actor | The Hollywood Squares | Square Placer (1975) | |
| Actor | Unlikely Angel | 1996 | Saint Peter |
| Actor | Inside Daisy Clover | 1965 | Walter Baines |
| Actor | My Friend Flicka | 1943 | Ken McLaughlin |
| Actor | 5 Card Stud | 1968 | Nick Evers |
| Actor | The Keys of the Kingdom | 1944 | Francis Chisholm, as a boy |
| Actor | That's Entertainment, Part II | 1976 | (archive footage) |
| Actor | Hart to Hart: Home Is Where the Hart Is | 1994 | Jeremy Sennet |
| Actor | Η Αιχμάλωτη του Πύργου | 1987 | Mr. Murray |
| Actor | Pretty Maids All in a Row | 1971 | Mr. Proffer |
| Actor | Laserblast | 1978 | Doctor Mellon |
| Actor | Charlie Chan and the Curse of the Dragon Queen | 1981 | Gillespie |
| Actor | Cricket on the Hearth | 1967 | Criket Crocket Narrator |
| Actor | Hollywood Wives | Jason Swandle | |
| Actor | Scavenger Hunt | 1979 | Jenkins |
| Actor | The Loved One | 1965 | D.J.Jr. |
| Actor | The Grass Harp | 1995 | Amos Legrand |