Is a member of McReary Family and seemingly the oldest. He has a drug and alcohol problem, so Packie asks Niko to keep an eye out for his brother's safety. Derrick has recently returned from Ireland where he assisted the IRA in fighting the British. Two of Derrick's old friends, Bucky Sligo and Aiden O'Malley, believed that Derrick snitched on them to the authorities and constantly threatened him and his family as result, despite Derrick's claims of innocence. The false accusations from his former friends caused him tremendous grief and fueled his drug addictions. He seems to be the most compassionate of all the McReary children, as is shown with the way he tries to calm down the bank staff and customers during the heist. When his brother, Francis, discovers that Derrick is back in town, he worries that he will reveal Francis' corruption to the press for money. He talks with Derrick in a park as part of an attempt to use Niko to kill him, thinking that he must go outside the law to take down his brother. Niko has a choice of who to kill. The player does not receive anything from Derrick for killing Francis.