Del Marquis (born Derek Gruen on August 31, 1977) is an American musician and the lead guitarist for the pop/rock group Scissor Sisters.

Born in New York City, he was introduced to the Scissor Sisters in 2001 at the insistence of a friend who, at the time, was dating Jake Shears.

[1] Gruen produced the DVD Kuvaputki released in 2008 by Embryoroom director Edward Quist about Finnish noise artists Pan Sonic.

[2] On Halloween 2008, he began releasing solo material, starting with the song "Hot House", only available with a digital film from his official site.

[4] The Runaround EP was released in September 2009,[needs update] and includes remixes from Baron von Luxxury and Lifelike.