Segueing to features, he appeared in over 15 British films in the mid- to late 1930s, including "Convict 99" (1937) and "Murder in the Family" (1938). With his mother and older sister, McDowall was evacuated to the USA. Almost immediately upon his arrival in Hollywood, he was signed to a contract by 20th-Century Fox. McDowall first came to the attention of American audiences as the cabin boy who helps Walter Pidgeon escape from the Nazis in Fritz Lang's superb "Man Hunt" (1941). Pidgeon and McDowall were again teamed in John Ford's Oscar-winning "How Green Was My Valley" (also 1941), this time with the older actor as a minister encouraging the youth in his attempts to overcome a crippling accident. The film established McDowall as a rising young lead, at once sensitive but also manly, and engendered comparisons with other child actors from Shirley Temple and Freddie Bartholomew. Throughout the 40s, he appeared in a number of well-crafted films, many centered around animals like "Son of Fury" (1942) and "Lassie Come Home" (1943). By the end of the decade, as he approached adulthood, McDowall attempted more interesting fare including a turn as David Balfour in the beautifully photographed but slow remake of "Kidnapped" (which also marked his producing debut) and as Malcolm in Orson Welles' "Macbeth" (both 1948). Slowly, though, despite producing a number of efforts, good feature roles became scarce.
McDowall turned to the stage and to television to further hone his craft. In 1951, he studied with famed acting teacher Mira Rostova and began finding work in TV anthology series. McDowall made his stage debut in summer stock in Westport, CT in 1946 and had toured in the waning days of vaudeville, but it wasn't until 1954 that he made it to the New York stage. After appearing in the inaugural season of the American Shakespeare Festival, he went on to co-star in the Broadway play "Compulsion" (1957) and earned a Supporting Actor Tony Award for "The Fighting Cock" (1959-60). McDowall made his Broadway musical debut alongside Richard Burton and Julie Andrews in Lerner and Loewe's "Camelot" (1960). On the small screen, he excelled as Ariel in "The Tempest" (NBC, 1960) and earned a 1961 Emmy for "Not Without Honor" (NBC). Baby boomers may also recall McDowall as the villainous The Bookworm on the campy "Batman" (ABC, 1966).
When he returned to features in the early 60s, it was as a character player. He was suitably creepy as a punk enamored of heroine Doris Day in the uneven "Midnight Lace" (1960) and was a strong Octavian in the extravagant "Cleopatra" (1963). In 1968, McDowall was cast in what is probably one of his most remembered role, the simian scientist Cornelius in "Planet of the Apes", a role he reprised in the second sequel "Escape From the Planet of the Apes" (1971). For the fourth and fifth installments, "Conquest of the Planet of the Apes" (1972) and "Battle of the Planet of the Apes" (1973), the actor assumed the role of Caesar, the son of Cornelius. He also played a similar role in the short-lived 1974 TV version.
The prolific actor continued to work in all media into the 80s and 90s. He was the French magistrate and bar owner on the adventure series "Tales of the Gold Monkey" (ABC, 1982-83) and won critical acclaim and a legion of new fans as the washed-up horror movie actor-turned-TV host who is enlisted to battle Chris Sarandon's seductive vampire in the superior "Fright Night" (1985). Near the end of his career, he played the nosy town barber in "The Grass Harp" (1995) and was back among simians as an Englishman held captive by chimps in "Rudyard Kipling's 'The Second Jungle Book: Mowgli and Baloo'" (1997). A noted collector of Hollywood memorabilia and a fine raconteur, McDowall had been a frequent interview subject for documentaries on celebrities as well as on the A&E series "Biography".
McDowall was also an accomplished photographer, having worked for such magazines as LOOK, LIFE and VOGUE. He has also published four books of his celebrity portraits: "Double Exposure" (1966), "Double Exposure, Take Two" (1989) "Double Exposure, Take Three" (1992) and "Double Exposure, Take Four" (1993).