Brendan Jason Kiernan (born 10 November 1992) is an English professional footballer who plays as a midfielder for EFL League Two club Grimsby Town, on loan from Walsall. He spent his early youth career at Bromley, Fulham and Crystal Palace before joining AFC Wimbledon at the age of 16. He made his league debut for AFC Wimbledon as a substitute on 18 March 2011, at the age of 18. He joined Walsall on 1 July 2021.