Kai Michael Hansen (born 17 January 1963) is a German musician who is the founder, lead guitarist and vocalist of power metal band Gamma Ray.

Hansen and Kiske reunited with Helloween in 2017 for a world tour with all current members, celebrating the 30-year anniversary of release of the albums Keeper of the Seven Keys Parts I and II.

[1] Hansen's musical career started in 1978 in a band called Gentry, alongside Iron Savior's co-founder and producer Piet Sielck.

Around the same time, he and fellow Gamma Ray bandmate Dirk Schlächter collaborated on Angra's first full-length album Angels Cry, both playing guitar solos in the song "Never Understand".

He was also one of the guest musicians in Avantasia's 2010 world tour, which have put him to play live together with fellow ex-bandmate Michael Kiske, after more than twenty years since he left Helloween.

After this tour it was announced, via Michael Kiske's official website, that Hansen would join his new band Unisonic, as they "instantly felt the magic of Helloween years again and had a lot of fun together on and off stage".

Rather than using a smooth and clear style (like his successor Kiske) Hansen sang with a raspy sound, interluded by high-pitched screams for dramatic effect.

Kiske was brought in as a singer, originally because Hansen had trouble singing and playing the guitar simultaneously, though later in his career he seems to have overcome these problems.

He first started using them during his days with Helloween after hearing testimonials of ESP from artists such as George Lynch and Kirk Hammett of Metallica.

Before Helloween, he had owned a white Ibanez guitar, and a Gibson Les Paul, then saved up for a Marshall amplifier by delivering newspapers.