Thomas G. Hannan (born January 14, 1980) is an American former competition swimmer and Olympic gold medalist.

Hannan won gold medals at the 1999 World University Games and the Swimming at the 2000 Summer Olympics.

He swam for Eagle Swim Team, EST, for a considerably long amount of time.

[2] He now resides in Seattle, Washington, and coaches the Power and National groups for KING Aquatic Club.

This biographical article related to a United States swimmer is a stub.