Peter Lewis Kingston Wentz III (born June 5, 1979) is an American musician. He is best known for being the bassist, lyricist, and backing vocalist for the American rock band Fall Out Boy. Before Fall Out Boy's inception in 2001, Wentz was a fixture of the Chicago hardcore scene and was the lead vocalist and lyricist for Arma Angelus. During Fall Out Boy's hiatus in 2009–12, Wentz formed the experimental, electropop and dubstep group Black Cards. He owns a record label, DCD2 Records, which has signed bands including Panic! at the Disco and Gym Class Heroes. Fall Out Boy returned in February 2013.

Wentz has also ventured into other non-musical projects, including writing, acting, and fashion; in 2005 he founded a clothing company called Clandestine Industries. He also hosts the TV show Best Ink and runs a film production company called Bartskull Films, as well as a bar called Angels & Kings. His philanthropic activities include collaborations with Invisible Children, Inc. and UNICEF's Tap Project, a fundraising project that helps bring clean drinking water to people worldwide, People magazine states that "no bassist has upstaged a frontman as well as Pete Wentz of Fall Out Boy." He is also a minority owner of the Phoenix Rising FC, a United Soccer League team.