Brennan Cox (born 13 August 1998) is a professional Australian rules footballer playing for the Fremantle Football Club in the Australian Football League (AFL).
Originally from Woodville South in Adelaide, Cox played for Woodville-West Torrens in the South Australian National Football League (SANFL) in 2016. He also represented South Australia at the 2016 AFL Under 18 Championships and was named as the centre-half back in the All-Australian team.
He was recruited as a versatile player to Fremantle with their third selection, 41st overall, in the 2016 AFL draft. He made his AFL debut in round 12 of the 2017 AFL season against Brisbane at the Gabba