Thomas William Arnold Thacker (born April 11, 1974),[1][2] nicknamed Brown Tom, is a Canadian musician, songwriter, and producer.

Following Dave Baksh's departure from Sum 41 on May 11, 2006, Thacker was recruited as their touring guitarist, and then became an official member in 2009.

Early in his career, he played drums in the Canadian pop punk band The McRackins, contributing to two studio releases.

He formed the band in 1993 with Theo Goutzinakis, Wolfman Pat Integrity on drums, and Kelly Macaulay on bass.

That year, Sum 41 received a Grammy Award nomination in the Best Hard Rock/Metal Performance category for the song "Blood in My Eyes".

[11] Thacker went by the name T'Aint (who replaced Steve Jocz's alter-ego Pain) in Sum 41's alter-ego heavy metal band Pain For Pleasure, where the members of Sum 41 would parody a 1980s metal band.

Under the name Tommy, Tom Thacker played drums in the Canadian pop punk The McRackins for their 1995 album What Came First?.