Dan Singer (born December 20, 1971), known professionally as Danny Diablo and Lord Ezec, is an American hardcore punk and hip hop vocalist based in New York City.

In 1994, Singer formed New York hardcore band Crown of Thornz consisting of former Breakdown guitarist Mike Dijan, drummer Dimi, and bassists Steve O'Brien and Franklin Rhi.

In 1995, the band released their debut EP Train Yard Blues on Equal Vision Records, dedicating it to Singer's younger brother David, who had committed suicide the previous year.

In 2013, Crown of Thornz reunited for Ieperfest in Belgium, This Is Hardcore Fest in Philadelphia, and a North American tour with Rancid and the Transplants.

In 1996, Singer collaborated with Jamey Jasta to form the metalcore band Icepick, which served as a side project of Hatebreed, alongside their bandmates Derek Kerswill, Wayne Lozinak, and Frank Novinec.