Ethan is a very prolific musician, and has several side projects, as do other people related to Barlow.
Gaadge is an indie rock/shoegaze band fronted by Mitch DeLong. Ethan plays drums and Andy plays guitar/keyboards in this band. Barlow did a split with Gaadge in 2018, and the song "Fancy" was reworked into the Gaadge song "Don't Go There."
Ex Pilots is an indie rock/shoegaze band fronted by Ethan. It features Andy on drums and the other members of Gaadge in the band, plus Ralph DiLullo on guitar as well. There is a lot of overlap in recorded material with Barlow and Ex Pilots; Findlay, which was originally released on the Barlow bandcamp before being rereleased as an Ex Pilots album, is almost split 50/50 between Barlow demos and Ex Pilots demos. The songs "Silver Sword" and "30 Days" were reworked into Ex Pilots Songs. Furthermore, Walls of Future and the first Ex Pilots album were very closely tied together, with several tracks originally being intended for one of them ending up on the other one. Despite this, Barlow and Ex Pilots haven't collaborated together yet, but Gaadge released a split with Ex Pilots in 2022.
Sober Clones is a lo-fi psychadelic rock band fronted by Ethan. Andy is also in this band as the drummer. Aside from having a similar lo-fi aesthetic, the Barlow song "Route 86" was incorporated into the Sober Clones song "Body Language."
LIVING WORLD is a hardcore punk band fronted by Ethan. Several L.W. songs originated as songs from a demo released by Ethan under the name "spaceman spliff." These demos would be rereleased by L.W., however, so spaceman isn't listed separately.
Little Angels is a hardcore punk band that Andy plays drums in.
BOX OF LAMB was a hardcore band fronted by Ethan. B.O.L. was before Barlow, and did not release much material, however a snippet of a B.O.L. song is featured in For All Time.
Sucko is a one-off Guided by Voices cover project of Ethan's. Ethan released a 52-track GBV cover album called "American Superdream" under this name in 2015, which is the only thing ever released by this project. Though the name "Sucko" is shared by the name of a Barlow song, it is actually a reference to one of GBV frontman Robert Pollard's many pseudonyms.