Louis Knox Barlow (born July 17, 1966) is an American alternative rock musician and songwriter. A founding member of the groups Dinosaur Jr., Sebadoh and The Folk Implosion, Barlow is credited with helping to pioneer the lo-fi style of rock music in the late 1980s and early 1990s. His first band, which was formed in Amherst, Massachusetts, was Deep Wound.

Barlow has released four solo albums.

Barlow was born in Dayton, Ohio on July 17, 1966, and raised in Jackson, Michigan, and Westfield, Massachusetts.

Barlow attended high school in Westfield, Massachusetts, where he met Scott Helland. The two formed the Massachusetts-based hardcore punk band Deep Wound. J Mascis joined the band after answering their ad for a "drummer wanted to play really fast". After becoming disillusioned with the constraints of hardcore, Deep Wound broke up in 1984. Mascis and Barlow reunited that year to form Dinosaur, later Dinosaur Jr. Mascis and Barlow had personality conflicts throughout Dinosaur Jr.'s early existence, and after the 1988 release of their third album, Bug, and the initial supporting tour, Barlow was kicked out of the band.

In 2005, Barlow rejoined the band alongside the original drummer, Murph. Since then, the band has reissued its first three records, toured extensively worldwide and released five new records, Beyond, Farm, I Bet on Sky, Give a Glimpse of What Yer Not, and Sweep It Into Space .

After his dismissal from Dinosaur Jr., Barlow turned his attention to his band Sebadoh, which he had formed earlier with multi-instrumentalist Eric Gaffney. The project featured low fidelity recording techniques and combined Barlow's introspective, confessional songwriting with Gaffney's discordant noise collages. Bassist and songwriter Jason Loewenstein was added to the line-up in 1989. Sebadoh's early releases include The Freed Man (1989) and Weed Forestin' (1990), the latter of which was originally self-released under the name Sentridoh in 1987. Both albums were officially released by Homestead Records, as was the band's third album, Sebadoh III (1991), which helped establish the "lo-fi" subgenre and became a defining album of 90s indie rock. The band released several studio-recorded albums on Sub Pop Records throughout the 1990s.

As Sebadoh grew in popularity and critical acclaim, Barlow continued work on the Sentridoh side project, which featured mostly home-recorded material similar to his output on the first three Sebadoh albums, but often recorded solo and with a less consistent sound quality. Sentridoh released a trio of cassette-only albums on Shrimper Records in the early 1990s, with the highlights later being collected on CD and vinyl compilations like Winning Losers: A Collection of Home Recordings 89–93 (1994) and Another Collection of Home Recordings (1994). In 1993, Sentridoh released a popular single for the song "Losercore," on the label Smells Like Records founded by Steve Shelley of the American rock band, Sonic Youth. Barlow has called it "the most finely executed of all my releases" thanks to Shelley, who "made sure this looked and sounded great." Numerous other Sentridoh releases on a variety of record labels followed, including releases on his own Loobiecore label.

In 1994, Barlow formed the Folk Implosion with singer-songwriter John Davis. The band released several singles and EPs, and in 1995 reached the Top 40 with the song "Natural One", from the soundtrack to the film Kids by Larry Clark. It remains Barlow's biggest commercial hit.