Matthew Walter "Matt" Wachter (born January 5, 1976) is an American musician best known for playing bass in the alternative rock bands Thirty Seconds to Mars and Angels & Airwaves.

His interest in music bloomed when he was around five years old, and between the ages of five and eight, he experimented with various instruments, focusing primarily on the piano and drums.

Wachter reached the peak of his musical interest around high school and spent most of his time playing in bands.

He credited former Metallica bassist, the late Cliff Burton, as his inspiration for wanting to play the bass guitar.

In the early days of Thirty Seconds to Mars, Wachter complained of consistent headaches after performing, but no pain while he was on stage.

The injury resulted from changing one of his car's headlights (or as Shannon Leto says "He was left alone with a pair of scissors."

While on tour in El Paso, Texas, on March 1, 2007, Jared Leto announced to the arena that Wachter would be playing his last show with the band.

This was confirmed by DeLonge on April 18, 2018, posting that both Wachter and guitarist David Kennedy had rejoined Angels & Airwaves and would appear on the next album.