Child actress of the stage and several features of the 1920s and 30s who, after playing in Broadway's "Susan and God" (1937), began her film career in earnest. Pretty without being beautiful, with brunette hair and full lips, Kelly was signed by 20th Century-Fox and played opposite Richard Greene in a lesser John Ford, "Submarine Patrol" (1938). She did the best she could with her modest role as Spencer Tracy's requisite romantic interest in the superior biopic "Stanley and Livingstone" (1939) and also acted in the big Westerns "Frontier Marshal" and "Jesse James" (both 1939). Unlike the similarly utilized Olivia de Havilland, however, Kelly never quite established herself as a major star.
The female aviator romantic drama "Tail Spin" (1939), in which, cast opposite Alice Faye and Constance Bennett, she more than held her own while carrying the bulk of the melodrama, didn't quite come off, and "He Married His Wife" (1940) saw Kelly a bit strained in her big bid to be a screwball heroine. She played second fiddle to Maureen O'Hara in "To the Shores of Tripoli" (1942) and she and Fox parted company soon thereafter.
Kelly did pretty well for herself for a time, performing delightfully in Robert Siodmak's "B" adventure gem, "Fly by Night" (1942). Other good films included the charmingly nostalgic musical "Show Business" (1944) and the unjustly neglected mystery "The Woman Who Came Back" (1945), but she saw the writing on the wall when she took a back seat to skater Vera Hruba Ralston in "Murder at the Music Hall" (1946).
The stage provided Kelly with much meatier roles in "The Big Knife" and "Season in the Sun", and she won a Tony for her excellent performance as a distraught, disbelieving mother who discovers that her young daughter is genuinely evil in "The Bad Seed" (1955). Contrary to custom, Kelly managed to recreate the role in the slightly compromised but still powerful 1956 film version. She preferred theater work, though, but did make sporadic TV appearances through the late 1970s. Married briefly to actor Edmond O'Brien (1941-42), she is the elder sister of actor Jack Kelly of "Maverick" fame.