Emil Werstler is an American guitarist and musician based in Nashville, Tennessee who is perhaps best known for his work in metal and gypsy jazz. In 2004, Werstler became lead guitarist for the metal band Dååth, whose second album The Hinderers peaked at No. 49 on the Top Heatseekers chart in 2007. In 2009 Dååth released The Concealers on Roadrunner which reached No. 35 on Top Heatseekers and was placed as No. 3 on a list of the "top twenty metal albums of 2009" by Metal Sucks. In 2010 Werstler released the instrumental metal album Avalanche of Worms as a collaboration with Eyal Levi with the album receiving a largely positive response for its musicianship and experimental nature.

By 2011 Werstler had been confirmed as the new lead guitarist for the metal band Chimaira. With Werstler as a co-writer, Chimaira's final album Crown of Phantoms was released in 2013, reaching No. 52 on the Billboard 200 chart. Werstler announced his departure from Chimaira in late 2014, with the rest of the band dissolving shortly afterwards.

Since 2006 Werstler has worked with artists such as Arsis, Austrian Death Machine, Enders Game, Jason Bieler, Sylencer, The Agony Scene, Unearth, and Xerath. In 2018 Werstler launched his solo project Verlorener. In addition to teaching privately Emil has contributed to guitar publications such as Premier Guitar, Guitar World, and JamPlay. He releases content periodically on his YouTube channel, teaches clinics across the US, and has performed at various events including Experience PRS.

Emil Werstler was born and raised in Alabama. He comes from a musically inclined family, and at a young age was exposed to diverse music by artists such as Stevie Wonder, Steely Dan, Mahavishnu Orchestra, and Led Zeppelin. At age six he began learning piano, an instrument he described being un-enthused about for the several years he attended lessons. At age twelve he began teaching himself guitar with a Washburn Lyon guitar and a ROSS keyboard amp, later stating that "I had no idea what a setup was nor did I even know there were guitars that were easier to play. I was just concerned about learning anything I could."

Early on he taught himself songs from heavy metal albums like Testament’s Low and Pantera’s Far Beyond Driven, and also "wound up really getting into more harmonically technical bands like Death and Cynic." As he grew further accustomed to other tracks, he developed an interest in the jazz recorded by artists such as Pat Martino. Self-taught on guitar throughout middle school and high school, Werstler began teaching the instrument at about age fifteen. At eighteen Werstler moved from Alabama to Atlanta, Georgia, to attend college at the Atlanta Institute of Music. While in college he took a break from playing metal to focus on older genres such as jazz and bebop.

While studying music in Atlanta, Werstler was introduced to metal musician Eyal Levi through a mutual friend. Though Werstler was not looking to focus on the metal genre in particular, he ended up giving Levi some guitar lessons. After some time passed, in 2004 Levi asked Werstler to join the death metal band Dååth, with Werstler taking on the role of co-lead guitarist. On April 25, 2004, Dååth self-released their debut album Futility, touring in support of the release.

While continuing to perform with Dååth, in 2006 Werstler was a guest guitar soloist on the Arsis album United in Regret. United in Regret received favorable reviews from press worldwide, including The Village Voice and Pop Matters.

Dååth's sophomore album The Hinderers was released on March 20, 2007, on Roadrunner Records, peaking at No. 49 on the Top Heatseekers chart. AllMusic gave the album a near-perfect score of 4.5/5, writing that "the intricately sculpted guitar collaborations of... Eyal Levi and instinctive lead guitar wunderkind Emil Werstler complement [co-founder Mike Kameron]'s considerable orchestrating abilities perfectly."