Sigrid "Sigi" Koizar, born in Lower Austria, is an Austrian basketball player. She began her career with Arkadia Traiskirchen and later played for Vienna 87. An exchange year led her to Stearns High School in Maine, USA, in 2011/12. From 2013 to 2017, she played for the University of Maine, where she averaged 12.9 points in 130 games and received multiple awards. After college, she continued her professional career in Europe, with stints in Hungary, Russia, France, Spain, Italy, Australia, and Romania. In 2023, she won the double in Romania with CSM CSU Constanța. Additionally, she has achieved numerous successes with the national team, where she also received the MVP award at the European Championship for Small Countries and reached 7th place at the 3x3 World Championship in 2023. She now plays in her home country for Klosterneuburg, where she also won the cup for her team.