Pierre Guillemin (13 September 1887 – 18 August 1915) was a French rugby union player, who represented France, Paris and Racing Club de France (RCF).
He was first selected to play for France in the Home Nations Championship of 1908, playing in the games against England and Wales. The following year, he played against England and Ireland, and in 1910, in all four Home Nations games. That year, he scored his only points for France, a try, against England in a close-fought match, after which he gained a reputation for being amongst the best of the French forwards.
Guillemin's final season playing for France was that of 1910–11. The French press disapproved of his selection, noting that he was excessively violent and not very effective. In 1911, France won its first ever official international match, beating Scotland 16–15 at home, but in the following game, away against England, the French were heavily beaten. Guillemin's last match for France was against Wales; he was dropped for the final game of the championship, against Ireland. He played on with RCF for one more season, playing in the team that was runner-up in the Championnat de France.
An architect by profession, he became a lieutenant in the French infantry, and died on the front in the First World War after a reconnaissance mission in Bois le Prêtre in Belleville-sur-Meuse.