Sturdy lead and character player who first gained attention as a squeaky-voiced juvenile on radio serials ("A Date with Judy", "Burns and Allen") and as the none-too-bright, love-sick teen Walter Denton on "Our Miss Brooks" (moving with the series when it transferred to TV, 1952-56). Although Crenna entered films in 1952 and made several features during the 50s (including a 1956 adaptation of "Our Miss Brooks"), he basically made the transition to adult roles as the star of such TV series as "The Real McCoys" (1957-63; as son Luke) and "Slattery's People" (1964-65; as an idealistic state representative).

In films regularly since the mid-60s, Crenna displayed his versatility as a criminal trying to get his hands on a heroine-stuffed doll in "Wait Until Dark" (1967), the noble commander of a spaceship running out of oxygen when it can't return to Earth in "Marooned" (1969) and the gang boss in Jean-Pierre Melville's swansong, "Un flic" (1972). In the 70s Crenna kept very busy, but in lesser fare including "The Man Called Noon" (1973), "Wild Horse Hank" (1979), and the TV-movies "Devil Dog: The Hound of Hell" (1978) and the tepid remake of "Double Indemnity" (1974).

Crenna's periodic attempts to find another hit TV series have failed ("All's Fair", "It Takes Two", "Pros and Cons"), but he has always been a reliable performer. In the late 70s Crenna appeared in more acclaimed TV work with the historical miniseries "Centennial" (1978) and the hard-hitting, socially relevant telefilm "A Case of Deadly Force" (1986). He won an Emmy for his fine performance in the well-intentioned "The Rape of Richard Beck" (1985) as a macho, sexist cop who must re-evaluate his ideas about rape victims when he becomes one himself. Tough cops became a staple for Crenna, especially his Lt. Frank Janek in a series of TV-movies lasting a decade beginning with "Doubletake" (1985). His feature film work was more visible as well: as the cuckold in the steamy noir remake "Body Heat" (1981), as the dishonest gin champion in Garry Marshall's ode to the 50s, "The Flamingo Kid" (1984), and as Colonel Trautman, Rambo's sympathetic Green Beret mentor in "First Blood" (1982) and its subsequent hyper-macho installments. To his credit, Crenna showed in "Hot Shots! Part Deux" (1993), in which he spoofs Trautman, that the gritty performance style of his middle years had not obscured his talent for farce.

Crenna has also worked as a TV director. He began doing episodes of "The Real McCoys" during its last two seasons, helmed episodes of "Wendy and Me", "No Time for Sergeants" and "The Andy Griffith Show" later in the decade, and continued into the 70s and 80s with series pilots and installments of various forgettable sitcoms and the drama series, "Lou Grant". A member of the Director's Guild of America, he provided the narration for their commemorative film, "50 Years of Action!" (1986).