Teemu Mäntysaari (Finnish pronunciation: [teːmu mæntysɑːri]; born 7 January 1987) is a Finnish guitarist.

He is known for playing for metal bands Wintersun, Imperanon, Induction, Smackbound, and Megadeth.

[4][5] On 5 September 2023, Mäntysaari stepped in as lead guitarist on Megadeth's North American tour as regular guitarist Kiko Loureiro tended to undisclosed family matters.

[6] On 21 November 2023, Megadeth band leader Dave Mustaine released an official statement, announcing that the band is "going to move forward with Teemu Mäntysaari as the guitar player for Megadeth" while Loureiro stays on an indefinite hiatus.

[7] This became permanent as Loureiro announced his departure from Megadeth later that month.