Darold Durard Brown Ferguson Jr. (born October 20, 1988), known professionally as FERG (previously A$AP Ferg (/ˈeɪsæp/ AY-sap)), is an American rapper from Harlem, New York City. He is a lead member of the hip hop collective ASAP Mob, from which he adopted his moniker and signed a recording contract with Polo Grounds and RCA Records—the same labels that helped launch ASAP Worldwide—in January 2013. Two years prior, the group's cohorts, ASAP Rocky and the late ASAP Yams, effectively negotiated their own contract with the label.

His 2013 commercial single, "Work (Remix)" (featuring ASAP Rocky, French Montana, Schoolboy Q, and Trinidad James)—a remix of his 2012 debut single—was released in May of that year; it marked his first entry on the Billboard Hot 100 and received triple platinum certification by the Recording Industry Association of America (RIAA). The song led his debut studio album Trap Lord (2013), which saw positive critical reception and peaked within the top ten of the Billboard 200 along with his second album, Always Strive and Prosper (2016). His 2017 single, "Plain Jane" (remixed featuring Nicki Minaj) became his first Billboard Hot 100-top 40 single and led his commercial mixtape, Still Striving (2017). Ferguson's 2020 single, "Move Ya Hips" (featuring Nicki Minaj and MadeinTYO) peaked at number 19 on the chart—becoming his highest-charting single—while marking one of the largest downward movements in the chart's history the following week. He signed a management deal with Roc Nation the following year.

Outside of music, Ferguson founded the street fashion brand Traplord in 2012, which is namesake for his debut album. In 2013, he was named "Rookie of the Year" at the BET Hip Hop Awards.