Jack Coonan is a character portrayed by Justin Alvarez in the ABC crime series Castle. Jack Coonan, also referred to as Jackie Coonan, was a murder victim and a top enforcer for the Westies in the episode "Sucker Punch". He was stabbed multiple times by his brother, Dick Coonan, because Dick was bringing heroin into the Westies' territory, and Finn Rourke told Jackie to 'send a message' to those responsible. Jackie did not underestimate his 'little brother', being armed to the teeth when he knew he was the next target.