Kari Arvo Ilari Kärtsy Hatakka (born December 17, 1967 in Helsinki, Finland) is the vocalist and bassist for the Finnish music group Waltari, which he founded in 1986. In addition, he co-wrote the soundtrack for the video games Max Payne and Max Payne 2 with Kimmo Kajasto.

He is known for his unique vocals. His vocals range from low, demonic-esque to a loud, screeching voice, making lyrics harder to understand.