Thamar Zweistra is a Dutch dressage rider, born on December 3, 1982, in Dordrecht. She has represented the Netherlands in numerous international competitions, achieving notable results. In 2000, she won the silver medal in team dressage at the Junior European Championships and placed fifth individually. In 2002, she secured silver in the team event and fourth place individually at the Young Riders European Championships. In 2003, she made history by becoming the Young Riders European Champion. In 2016, she placed her 21st horse in Grand Prix. In 2022, she competed at the FEI World Championships in Herning, finishing 20th in the individual dressage competition and 5th with the Dutch team.