German guitarist for the rock band Tokio Hotel. He played on the band's 2009 full-length album Humanoid.
He and his brother Bill played music at local shows in Germany.
Reebok featured him in a shoe commercial in 2010. He launched a fan app with his brother called BTK Twins.
He and Tokio Hotel band member Bill Kaulitz are identical twins born to parents Simone and Jorg Kaulitz. He was married to Ria Sommerfeld until their divorce in 2016. In 2018, he got engaged to Heidi Klum.
He's played with Georg Listing in Tokio Hotel.