Jil Belén Teichmann (born 15 July 1997) is a Swiss professional tennis player. She has been ranked by the Women's Tennis Association (WTA) as high as No. 21 in singles and No. 73 in doubles. She has won two titles in singles and two in doubles on the WTA Tour, along with one WTA 125 doubles title. In addition, she won six singles titles and five doubles titles on the ITF Circuit.
A former junior world No. 3, Teichmann won a Grand Slam title in the girls' doubles event at the 2014 US Open. That year, she also won a gold medal for Switzerland in mixed doubles at the Summer Youth Olympics in Nanjing.
Her breakthrough as a senior player came in May 2019 when she won her first WTA Tour title in Prague. In July of that year, she won another WTA tournament title after making her first top-10 win over Kiki Bertens. She continued progressing, in March 2021 reaching the semifinals of the WTA 1000 Dubai Championships. With these performances she entered the top 50. Later that year, she reached the final of the Cincinnati Open, a WTA 1000 event, defeating Naomi Osaka, Belinda Bencic, and Karolína Plíšková, before falling to world No. 1, Ashleigh Barty.