Katherine Sebov (born January 5, 1999 in Toronto, Ontario, Canada) is a Canadian professional tennis player. She reached a career-high WTA singles ranking of No. 136 on April 10, 2023 and a career-high WTA doubles ranking of No. 433 on May 27, 2019.
In 2017, Sebov reached her first professional final at the ITF 60K in Granby but was defeated by Cristiana Ferrando. In 2018 at the ITF 25K in Toyota, she reached her second final, losing to Dejana Radanović in three sets. In 2018, she won her first professional title at the ITF 60K in Saguenay, defeating Quirine Lemoine in the final. In 2019, Sebov advanced to her fourth ITF final, losing to İpek Soylu in three sets at the W25 in Figueira da Foz. Also in 2019 at the W25 in Sakatoon, Sebov reached her fifth ITF final where she was defeated by Maddison Inglis. In 2021, she captured her first pro doubles title, winning with Maja Chwalińska at the ITF W25 in Jablonec nad Nisou. In 2022, she advanced to her sixth ITF final but lost to Han Na-lae at the ITF W25 in Monastir. The same year, Sebov reached the final of the ITF W60 in Saguenay for the second time of her career but was defeated by Karman Thandi. Also in 2022, she won the second ITF singles title of her career thanks to a victory over Michaela Bayerlová at the W25 in Tauranga. In 2023, Sebov claimed her third ITF singles title with a win over Himeno Sakatsume at the W25 in Toronto. The same year, she reached the biggest final of her career to date at the ITF W100 in Granby where she lost to Kayla Day in three sets. Also in 2023, she won the fourth singles title of her career, and her second at the ITF W60 in Saguenay, with a straight sets victory over Fanny Stollár.