+44 was an American rock supergroup formed in Los Angeles, California, in 2005. The group consisted of vocalist and bassist Mark Hoppus and drummer Travis Barker of Blink-182, lead guitarist Shane Gallagher of The Nervous Return, and rhythm guitarist Craig Fairbaugh of Mercy Killers. Hoppus and Barker created +44 shortly after the initial 2005 breakup of Blink-182 and before it was later reformed. The band's name refers to the international dialing code of the United Kingdom, the country where the duo first discussed the project. Early recordings were largely electronic in nature, and featured vocals by Carol Heller, formerly of the all-girl punk quartet Get the Girl.

Mark Allan Hoppus is an American musician, songwriter and producer who is known as the bassist and co-lead vocalist for the rock band Blink-182, being the only member to appear on every one of their albums. He is also part of the pop rock duo Simple Creatures.