Brianne Theisen-Eaton (born 18 December 1988) is a retired Canadian track and field athlete who competed in the heptathlon and women's pentathlon.

[2] Theisen-Eaton won Commonwealth Games gold in the heptathlon at Glasgow 2014 and was the 2016 World Indoor Champion in the pentathlon.

She enrolled at the University of Oregon and broke a number of school records in her first three years, winning back-to-back NCAA heptathlon titles in 2009 and 2010.

[6] She found her niche in the track and field combined events and represented Canada at the 2005 World Youth Championships in Athletics, finishing seventeenth in the girl's heptathlon.

[9] Theisen-Eaton received a sports scholarship at the University of Oregon, where she started a major in business administration in late 2007.

Theisen began her second year with a third-place finish in the pentathlon at the NCAA Women's Indoor Track and Field Championship.

[6] This earned her a spot on the national team to make her senior international debut at the 2009 World Championships in Athletics.

[6] Theisen continued her strong college form into the following year, winning her first pentathlon title at the 2010 NCAA Indoors with 4396 points and repeating as the Pac-10 Outdoor heptathlon champion.

[6] That year, she also led Oregon to a decathlon/heptathlon double at the Texas Relays, as she claimed the win alongside her schoolmate Ashton Eaton[13] to whom she was engaged.

[14][15] In 2011, she won at the NCAA Indoor Championships for a second time and broke Jacquelyn Johnson's collegiate record mark with a total of 4540 points from five events.

[19] Theisen placed second at the Canadian Track and Field Championships and went on to finish eleventh in the heptathlon at the 2012 London Olympics.

[23] At the 2014 World Indoor Championships in Poland, Theisen captured silver in pentathlon with a personal best score of 4768, breaking her own national record.

[24] She next competed at the 2014 Commonwealth Games in Glasgow where she went on to win the gold medal in the women's heptathlon event ahead of compatriot Jessica Zelinka.

She went into the 2015 World Championships in Athletics as the favourite to win, having achieved higher scores than rival Jessica Ennis-Hill since Hill's return from pregnancy.

[31] The two of them starred in a Visa Inc. advertisement that aired during the 2016 Summer Olympics, which poked fun at their romance despite representing different countries.