Troy Bryan Downing (born March 4, 1967) is an American politician and businessman serving as a member of the U.S. House of Representatives for Montana's 2nd congressional district since 2025. A member of the Republican Party, he previously held the office of Montana state auditor from 2021 to 2025.

Downing ran for the United States Senate in 2018, but placed third in the Republican primary, behind then-state auditor Matt Rosendale and Yellowstone County District Judge Russell Fagg. In 2020, Downing ran for State Auditor of Montana to succeed Rosendale, who was running for the House of Representatives. He won the Republican nomination, defeating 2 other candidates, and defeated Democrat Shane Morigeau in the general election. In 2024, instead of running for a second term, Downing instead ran for the House of Representatives, also to succeed Rosendale, who retired after 2 terms. He won the Republican nomination and defeated former state house speaker John Driscoll. He and Tim Sheehy are expected to be the co-deans of the Montana's congressional delegation in 2027 after Steve Daines and Ryan Zinke announced their retirements.

Downing was born in Indio, California. He studied applied mathematics and computer science at New York University.

Downing was a research scientist and educator at the Courant Institute of Mathematical Sciences at New York University. After leaving college, Downing founded WebCal, a web calendar company that was later acquired by Yahoo!. Downing later founded a nationwide commercial insurance company and a real estate firm. He enlisted in the United States Air Force after the September 11 attacks and was assigned to a combat search and rescue squadron. During his service, Downing worked as a flight engineer and was deployed to Afghanistan twice. He is the founder and former CEO of AC Self Storage Solutions, a self-storage and real estate investment firm based in Carlsbad, California.

Downing is the co-owner of Wildrye Distilling in Bozeman, Montana, which manufactured thousands of gallons of hand sanitizer during the height of the COVID-19 pandemic in Montana.

Downing was a candidate in the 2018 United States Senate election in Montana, placing third in the Republican primary.

During the 2020 election, Troy Downing defeated Scott Tuxbury and Nelly Nicol in the Republican primary for Montana state auditor. On June 2, 2020, Downing became the Republican nominee, winning 55 of 56 counties and receiving 50% of the vote in the three-way primary.

In the general election, Downing defeated state Senator Shane Morigeau. He was sworn in as state auditor on January 4, 2021.