Patrick Cavendish was a member of the Rapture police force. He was a large, half-Irish, half-Suffolk man with blue eyes and a leering smile. Sullivan disliked Cavendish, noting that he liked to beat up prisoners but that he was a good man in a fight. Cavendish became Head Constable after Constable Harker was killed by a ricocheting bullet during a fight with a Houdini Splicer in 1956. Cavendish lost part of his left ear during the same fight.
Cavendish was part of a raid on Frank Fontaine's smuggling operations in Neptune's Bounty in 1956 during which several constables were drowned by a submerging fishing vessel. Later in 1958 Cavendish led a large assault on Fontaine's smugglers' on the wharf in Neptune's Bounty. During the ensuing battle with the Splicers, Cavendish killed Reggie, who had undergone surgery to look like Fontaine. The constables were forced to retreat under heavy fire from Fontaine's forces, giving them no chance to check the body.
After the 1958 New Year's Eve Riots, Cavendish was responsible for executing at least six constables who had acted as traitors during the fighting. As Andrew Ryan began cracking down harder on dissenters he authorized Cavendish to conduct torture session on prisoners. Ryan also gave Cavendish orders to acquire more young girls to be made into Little Sisters after Tenenbaum took many of them into hiding with her.
Cavendish was with Redgrave and Ivan Karlosky in the Lighthouse in when they went to stop Bill, Elaine, and Sophie McDonagh from escaping in 1959. Cavendish was shot in the head and killed by Karlosky after he insulted Redgrave.