Hall of Famer Merlin Olsen, who helped form one of the NFL's greatest defensive lines before embarking on a successful career in television, died Thursday after a battle with cancer. He was 69. Olsen was a member of the Los Angeles Rams' “Fearsome Foursome” along with Deacon Jones, Lamar Lundy and Rosey Grier in the 1960s. He later starred on NFL broadcasts, commercials, and as Jonathan Garvey on the TV series “Little House on the Prairie.” Utah State, Olsen's alma mater, said he died outside of Los Angeles. He was diagnosed last year with mesothelioma, a cancer of the lung lining often linked to asbestos. Olsen filed a lawsuit last year, claiming he contracted the disease as a result of being exposed to asbestos on construction sites where he worked as a child and young adult. Olsen was voted NFC defensive lineman of the year in 1973 and the NFL MVP in 1974, and was voted to the Pro Football Hall of Fame in 1982. Olsen made a few television cameos during his football career and turned to acting full time after he retired in 1976. He's best remembered for his role alongside Michael Landon and Melissa Gilbert on “Little House on the Prairie” from 1977-81, and on the short-lived “Father Murphy.” Olsen is survived by his wife, Susan, and three children. There was no word Thursday on funeral arrangements.