Kai Michael Hansen (born January 17, 1963, in Hamburg, West Germany) is a power metal guitarist and vocalist.

Hansen is the founder, lead guitarist, and vocalist of power metal band Gamma Ray, and the co-founder of German metal band Helloween who he rejoined in 2017 to tour with, having originally left in 1988.

He is a prominent figure in power metal, and has sold millions of albums worldwide. He is regarded as the grandfather of power metal, having founded two seminal bands in the genre.