David Janssen was born David Harold Meyer in 1931 in Naponee, Nebraska, to Berniece Mae (Graf) and Harold Edward Meyer, a banker. He was of German, and some Swiss-German and Ulster-Scots, descent. David took the surname of his stepfather, Eugene Janssen. The Janssen family settled in Hollywood when he was a teenager and he attended Fairfax High School, where he developed an interest in acting. His film debut was a bit part in It's a Pleasure (1945), and at the age of 18 signed a contract with 20th Century-Fox. However, the studio dropped him after allegedly becoming disenchanted with his odd hairline and big prominent ears. Janssen had better luck at Universal, where he signed on in the early 1950s and became a supporting player in 32 films before appearing on TV as the star of Richard Diamond, Private Detective (1956). He resumed his movie career in 1961, a year after the series ended. His biggest success came from his lead in the series The Fugitive (1963), playing the haunted, hunted Dr. Richard Kimble, on the run for a murder he didn't commit. After the series ended, Janssen launched himself into a grueling schedule by appearing in lead and supporting roles in movies, but he had better luck with made-for-TV-movie roles and a short-lived series, O'Hara, U.S. Treasury (1971). He had another hit series with the cult favorite Harry O (1973). Janssen continued appearing in lead roles in nearly 20 made-for-TV-movies during the 1970s as well as other TV projects. He died in 1980 from a sudden heart attack at his Malibu home at the age of 48. Unfounded speculation holds that Janssen succumbed to alcoholism, a problem that plagued him most of his adult life. There were even unfounded rumors about drug use. However, a much more reasonable explanation for David Janssen's sudden demise is that this intense, dedicated, determined actor simply worked himself to death.

From an IMDB Mini-Bio for David Janssen