Jeff Tweedy (born August 25, 1967 in Belleville, Illinois, United States) is an American singer-songwriter, musician, and poet best known for his work with the group Wilco. Tweedy joined rockabilly band The Plebes with high school friend Jay Farrar in the early 1980s, but Tweedy's musical interests caused one of Farrar's brothers to quit. The Plebes changed their name to The Primitives in 1984, and subsequently to Uncle Tupelo. Jeff is also a member of Golden Smog, an occasional musical collective whose shifting personnel also includes members of The Jayhawks, Soul Asylum and The Replacements. Jeff is also a member of Loose Fur, which includes Jim O'Rourke (Sonic Youth) and Glenn Kotche (Wilco).

Further, as part of (Wilco) Tweedy teamed up with Billy Bragg to set Guthrie family-held lyrics of Woody Guthrie's to new music on the critically acclaimed albums Mermaid Avenue and Mermaid Avenue Vol II.