The Doomsday Defense was the defensive lineup of the Dallas Cowboys American football team during the dynasty years of the late 1960s - 1970s. This defense was the backbone of the Cowboys' dynasty, which won two Super Bowls (VI, XII) and played in three more (V, X and XIII).^[1]

In 1964, sports writer Gary Cartwright of the Dallas Morning News coined the phrase "Doomsday Defense".^[2] The Doomsday Defense is often recognized as having two different "generations," but different listings of players and time periods exist.^[3] The original "Doomsday Defense" can generally be identified as the Cowboys' defenses from 1966 to 1974. "Doomsday II" had its heyday from approximately 1975 to 1982.^[4] Many Cowboy fans recognize the defense from 1992 to 1996 as "Doomsday III", though to a lesser extent. This defense was in part, responsible for the Cowboys being the first team to ever win three Super Bowls in a four-year span.^[5]

The first defensive player to be named Most Valuable Player (MVP) of the Super Bowl was linebacker Chuck Howley (V).^[6] Later linemen Harvey Martin and Randy White became the first (and only) teammates (co-MVPs) to win the award (XII).^[7]