Michael Edward "Mikey" Welsh (Syracuse, New York, 1971 – Chicago, 2011) was an American artist and musician, best known for playing bass in the rock band Weezer. After starting out in the Boston music scene, he joined Weezer in 2000 as a replacement for Matt Sharp and appeared on the band's 2001 self-titled album, known as the Green Album.
In 2001 he suffered a mental health crisis linked to drug use, undiagnosed mental health problems and the strain of touring. After a suicide attempt by drug overdose he left the band, and soon afterwards he gave up music to focus on painting.
His work is marked by highly spontaneous and aggressive painting, often done with his hands and fingers rather than a brush. He also made sculptures from found objects, such as broken chairs, hoses and plastic containers. He exhibited his work in many shows and was associated with Outsider Art. He died in 2011 in a Chicago hotel room, from a suspected heroin overdose.