Jack Monk (born 1938 age 68 in 2006) is Adrian Monk's father. Jack, the father of both Ambrose and Adrian Monk, abandoned his family while running to pick up an order of Chinese food. According to Jack, he never planned on leaving, but rather did so on impulse. Adrian was only eight years old and his father's abandonment is seemingly the catalyst for both Adrian and Ambrose's psychological illnesses. Both would blame themselves for their father's leaving for most of their lives, each believing it was because they drove him crazy. For the next four decades, Ambrose kept all his father's mail and kept his belongings at the house just the way his father left them.