Born in Havana, Cuba. Son of actress-poet Iris Tree and photographer Curtis Moffat; grandson of Sir Herbert Beerbohm Tree, actor-manager and founder of the Royal Academy of Dramatic Art -- RADA; great-nephew of writer-critic Max Beerbohm. Moffat was blacklisted for a time in Hollywood. He was an executive assistant at RKO for I REMEMBER MAMA (1948), and he worked at Paramount as associate producer for George Stevens' A PLACE IN THE SUN (1951) and SHANE (1953). His screen writing credits include BHOWANI JUNCTION, D-DAY THE SIXTH OF JUNE and GIANT (all 1956), BOY ON A DOLPHIN and THE WAYWARD BUS (both 1957), THEY CAME TO CORDURA (1959), TENDER IS THE NIGHT (1962), THE HEROES OF TELEMARK (1965), HITLER: THE LAST TEN DAYS (1973), BLACK SUNDAY (1977) and "Florence Nightingale" (1985, TV). He modified a substantial part of THE GREAT ESCAPE (1963), but chose to forgo a screen credit.  Nominated for Writing (Best Screenplay Adapted) 1956: GIANT (w. Fred Guiol) 1 nomination