Georg Albert Ruthenberg (born August 5, 1959), better known by his stage name Pat Smear, is an American musician. He was the lead guitarist and co-founder of Los Angeles–based punk band The Germs and a rhythm guitarist for grunge band Nirvana (which he joined as a touring guitarist in 1993). After Nirvana disbanded following the death of frontman Kurt Cobain, drummer Dave Grohl went on to form Foo Fighters, with Smear joining on guitar. Smear left the band in 1997 before rejoining as a touring guitarist in 2005 and being promoted back to a full-time member in 2010.

Smear was born and raised in West Los Angeles, California to a German Jewish father and African American and Native American mother. His parents enrolled him in piano lessons at a young age, and a few years later he began teaching himself to play the guitar.

At age 13, he left home to join a commune. Later, he attended Innovative Program School (IPS), an alternative school within University High School in Los Angeles. It was there he met vocalist Darby Crash, alongside whom he would play in the Germs in the late 1970s. Smear and Crash were both expelled from IPS due to concerns they were inciting unruly behavior among the students.

Smear lists his influences as Joan Jett, Brian James, Brian May, and Steve Jones. He also stated that "all the guitar playing" of John McKay on Siouxsie and the Banshees's first album "really inspired me" and that Yes guitarist Steve Howe is "the best guitarist ever". As a teenager in 1976, Smear and Darby Crash formed the Germs with bassist Lorna Doom and drummer Dottie Danger (the pseudonym of Belinda Carlisle, who would go on to front The Go-Go's). Smear was the only band member who had any musical knowledge or proficiency at the time. For most of his time in the Germs, Smear reported that he didn't own a guitar but rather "just borrowed from whoever we were playing with".

Carlisle was soon replaced by Don Bolles and, in 1979, the band released their first album, (GI), produced by Joan Jett. The record is now regarded as a milestone in the history of punk rock, with Smear earning praise for his guitar work: "Smear has an equal claim to being the album's star [alongside Darby], though, and for good reason – not only did he co-write everything, his clipped, catchy monster riffing was as pure punk in the late-'70s sense as anything, wasting no time on anything extraneous."

The Germs, along with Smear, appeared in the punk documentary The Decline of Western Civilization (1981), directed by Penelope Spheeris. Darby Crash died before the film was released, leading to the band breaking up.

Following the demise of the Germs, Smear played in 1981 with the ex-Screamers keyboardist Paul Roessler and his sister Kira Roessler in Twisted Roots. Although short-lived, the band was the toast of the Hollywood punk scene. He also had a brief stint as a member of punk band the Adolescents in 1981.

Smear was briefly in deathrock band 45 Grave with Don Bolles (the former drummer for the Germs). During this stint, they recorded a 7" titled Black Cross and other tracks that would later appear on 45 Grave's 1987 compilation album, Autopsy.