Mike Shanahan claimed that Raiders owner Al Davis owed him $250,000 when he was fired in 1988, and he made it his personal mission in life to torture that team for the rest of his career. Shanahan won 11 of his first 12 meetings against the Raiders when he took over as head coach of the Broncos, including en route to Super Bowl wins in 1997 and 1998.
Ironically the two families now seem forever tied at the hip, in part thanks to Jon Gruden, Jay Gruden, Sean McVay, Kyle Shanahan, and the four years that the latter two spent together in Washington.