Father John Misty
Joshua Tillman a.k.a. J. Tillman a.k.a. Father John Misty began releasing bleak, introspective solo records as early as 2004 before joining Fleet Foxes as a drummer and vocalist. In 2012, Tillman revamped his sound under new moniker Father John Misty, and hasn't looked back since. His debut as FJM, "Fear Fun," is one of the most outstanding singer-songwriter records of the past 20 years, blending darkly humorous lyricism ("I ran down the road, pants down to my knees / Screaming 'Please come help me, that Canadian shaman gave a little too much to me!'" opens "I'm Writing a Novel") with rootsy guitar-driven folk rock.
Poor Moon
Poor Moon is another Foxes spinoff, this one featuring keyboardist Casey Wescott and bassist Christian Wargo, both current members. Like Tillman's Father John Misty project, the band started as an offshoot after 2011's "Helplessness Blues" made Fleet Foxes household indie rock names. It's less pristine production-wise, but the rough edges pay off on tunes like "Heaven's Door" and "Holiday" in distinguishing the side project from that which made it possible. They've only released a handful of songs, but maybe we'll see more in the near future.
Bowerbirds
Just as catchy with nearly half the members, North Carolina trio Bowerbirds craft folk with similar sonic elements to FF, relying on acoustic instruments like fingerpicked guitar and accordian that let the driving melodies of their 2007 debut "Hymn for a Dark Horse" and career highlight "Upper Air" from 2009 take center stage. John Darnielle of The Mountain Goats, no stranger to acoustic but vivacious folk himself, lent them some pretty lofty praise, calling them his "favorite new band in forever."
The Incredible String Band
Fleet Foxes weren't the first band to blend folk with woodwinds and Eastern instruments like the Tibetan singing bowls. Scottish psych-folkers The Incredible String Band, initially active from 1966-1974, probably weren't either, but they made a career for themselves by dousing the '60s folk counterculture with a healthy dose of weirdness. By feverishly releasing 12 albums in eight years, ISB placed themselves squarely in the hippie scene in its prime and bands ranging from Led Zeppelin to freak-folk revivalists Devendra Banhart count them as an influence.
Horse Feathers
Portland group Horse Feathers, which formerly featured multi-instrumentalist/session musician Peter Broderick who has performed with M. Ward and Zooey Deschanel, have released four albums of introspective baroque folk heavy on strings and country music instruments. Frontman Justin Ringle sounds like a combination of Bonnie "Prince" Billy and Ray LaMontagne, and they hail from the Pacific Northwest region that would later breed the music of Fleet Foxes.