Kai Hahto (born 31 December 1973) is a Finnish musician, best known as the drummer of Wintersun and Nightwish.

In 2009-2012 Kai Hahto played about 300 shows with doom-death-metal band Swallow the Sun as a tour drummer.

Hahto has an endorsement relationship with Sihi cymbals, Pearl drums and hardware, Balbex drumsticks, Roland V-Drums and Finfonic earphones.

[citation needed] On 6 August 2014, it was announced that Hahto would play drums on the Nightwish studio album, Endless Forms Most Beautiful, replacing Jukka Nevalainen who went on hiatus from the band due to insomnia,[3] and Hahto performed on all live shows since that date.

[4] In December 2020, it was announced that Hahto would be the drummer for the new lineup in Finnish black metal band Darkwoods My Betrothed, who had become active again.