Michael Andrew "Duff" McKagan (born February 5, 1964) is an American musician. He was the bassist of hard rock band Guns N' Roses for twelve years, with whom he achieved worldwide success in the late 1980s and early 1990s. McKagan rejoined the band in 2016, following their induction into the Rock and Roll Hall of Fame.

Toward the end of his first tenure with Guns N' Roses, McKagan released the solo album Believe in Me (1993) and formed the short-lived supergroup Neurotic Outsiders. Following his departure from Guns N' Roses in 1997, McKagan briefly reunited with his pre-success Seattle punk band 10 Minute Warning, before forming the still-active hard rock band Loaded, in which he performs lead vocals and rhythm guitar. Between 2002 and 2008, he played bass in the supergroup Velvet Revolver with his former Guns N' Roses bandmates Slash and Matt Sorum. He briefly performed with Alice in Chains in 2006, with Jane's Addiction in 2010, and with the supergroup Hollywood Vampires in 2016. He has also collaborated in several short-lived projects with fellow Seattle-native musicians Mike McCready (primarily of Pearl Jam) and Barrett Martin (formerly of Screaming Trees), including Walking Papers and Levee Walkers.

In addition to his musical career, McKagan has established himself as a writer. He has written weekly columns on a wide variety of topics for SeattleWeekly.com, Playboy.com, and ESPN.com. Previously a high school drop-out, he attended Seattle University's Albers School of Business and Economics in the early 2000s, and subsequently founded the wealth management firm Meridian Rock.