Matthew Brennan, born as Max Keenan, is Joy Keenan/Temperance Brennan's and Kyle Keenan/Russ Brennan's father. He and his late wife Ruth Keenan/Christine Brennan, disappeared when Temperance and Russ were very young, after going out to "run errands". It is revealed that they were career criminals who went into hiding after committing many crimes as fugitives. Though his wife died from skull trauma in 1993, Matthew continued living in hiding for years, until Russ' life was threatened. Matthew gave Temperance a tape from her mother that was supposed to be for her sixteenth birthday.