Frank Anthony Grillo (born June 8, 1965) is an American actor. He is known for playing Brock Rumlow/Crossbones in three superhero films and one series of the Marvel Cinematic Universe (MCU), Sergeant Leo Barnes in two action-horror films within The Purge franchise, and Rick Flag Sr. in the DC Universe (DCU). He has also appeared in Warrior (2011), The Grey (2012), End of Watch (2012), Zero Dark Thirty (2012), Wolf Warrior 2 and Wheelman (both 2017), and Boss Level (2021).

Grillo's television work includes the lead role in Kingdom (2014–2017) and recurring roles in Battery Park (2000), For the People (2002–2003), The Shield (2002–2003), Prison Break (2005–2006), Blind Justice (2005), The Kill Point (2007), and Billions (2020).