Leo Thomas Sullivan III (born May 17, 1956) is an American politician and a Democratic member of the Colorado Senate.

He represents District 27, which includes all or parts of Aurora, Centennial, Dove Valley, Inverness and Foxfield in Arapahoe and Douglas counties.

Sullivan is known for his advocacy and legislation surrounding gun control, which began following the death of his son in the 2012 Aurora, Colorado shooting.

Representative Sullivan focuses on the issues of crime victims' rights, worker protections, veterans affairs, and expanding access to mental health treatment.

With help from the GI Bill, he attended Metropolitan State University of Denver and studied accounting and journalism.

Sullivan went on to run for Tate's old seat in House District 37 in 2018, and won against the incumbent, Cole Wist, with 54% of the vote.

[4] In the 2022 general election, Sullivan won the race for Senate District 27, defeating Republican nominee Tom Kim with roughly 55.5% of the vote.

ERPO, also referred to as the “Red Flag” law, is one of the most progressive pieces of gun legislation to come from the Colorado General Assembly.

Effective since January 1, 2020, the red flag law has given family and household members the ability to file a petition for an extreme risk protection order against a gun owner under a reasonable basis.