Matthew Ryan Phillippe (/ˈfɪlɪpi/; born September 10, 1974) is an American actor. After appearing as Billy Douglas on the soap opera One Life to Live (1992–1993) and making his feature film debut in Crimson Tide (1995), he came to prominence in the late 1990s with starring roles in I Know What You Did Last Summer (1997), 54 (1998), Playing by Heart (1998), and Cruel Intentions (1999).

Throughout the 2000s and beyond, he took on a range of roles in films such as The Way of the Gun (2000), Antitrust (2001), Gosford Park (2001), Igby Goes Down (2002), The I Inside (2003), Crash (2004), Flags of Our Fathers (2006), Breach (2007), Stop-Loss (2008), MacGruber (2010), The Bang Bang Club (2010), and The Lincoln Lawyer (2011).

Outside of film, Phillippe appeared in the lead role of Bob Lee Swagger on USA Network's Shooter (2016–2018) and reprised his portrayal of Dixon Piper in the Peacock adaptation of MacGruber (2021).

In 1997, Phillippe met actress Reese Witherspoon at a party for her 21st birthday. Phillippe and Witherspoon, who was six months pregnant, married on June 5, 1999. Their daughter Eva was born in 1999 and their son Deacon was born in 2003. On October 30, 2006, the couple released a statement announcing that they were formally separating. Witherspoon filed for divorce on November 8, 2006, citing  irreconcilable differences as the cause. The couple's marriage officially ended on October 5, 2007, with final divorce arrangements settled on June 13, 2008, according to court documents. They shared joint custody of their children.