Kateřina Siniaková, Czech tennis player
Kateřina Siniaková (Czech pronunciation: [katɛˈr̝ɪna sʲɪˈnʲakəvə]; Russian pronunciation: [kətʲɪˈrʲinə sʲɪnʲɪˈkovə]; born 10 May 1996) is a Czech professional tennis player who is the current world No. 1 in doubles.

Siniaková is a four-time Grand Slam champion, having won the 2018 French Open, 2018 Wimbledon Championships, 2021 French Open and 2022 Australian Open in women's doubles, alongside compatriot Barbora Krejčíková. Siniaková also finished runner-up in doubles at the 2017 US Open with Lucie Hradecká, and at the 2021 Australian Open and 2018 WTA Finals with Krejčíková. In singles, her best major result was at the 2019 French Open, where she upset then-world No. 1 Naomi Osaka en route to the fourth round. She has reached the third round at five other majors.

Siniaková became world No. 1 in doubles on 22 October 2018 and held the top ranking for the next 33 weeks. She has won 16 doubles titles on the WTA Tour, including the 2021 WTA Finals and two at WTA 1000 level. Siniaková reached her career-high singles ranking of world No. 31 in October 2018, and has won two WTA titles in singles, at the Shenzhen Open and Swedish Open in 2017. She was part of the Czech team which won the 2018 Fed Cup, and won an Olympic gold medal in women's doubles alongside Krejčíková at the 2020 Tokyo Olympics.