Kelly John Breen (born May 13, 1969, in Perth Amboy, New Jersey) is a trainer of thoroughbred racehorses.

[2] As a New Jersey native, he operated a small stable from 1992 to 1994.

He then worked as an assistant to Ben Perkins before taking over as the personal trainer at Monmouth Park in 2003.

By 2006, he was training horses exclusively for George and Lori Hall.

[4] Breen no longer trains privately for the Halls, and has won several graded stakes including those with Bern Identity, Black Onyx, Stonetastic and Calamity Kate.