Mateusz Maurycy Śmierzchalski (born 18 July 1982, Gdynia, Poland), stage name Havoc, is a Polish heavy metal musician.

He is best known for being the former rhythm guitarist for Behemoth.

[1] Since 1999, he is lead guitarist of the sludge-doom metal band Blindead.

[2] Mateusz Śmierzchalski is endorsed by Mayones.

[3]