Catalina Castaño Álvarez (Latin American Spanish: [kataˈlina kasˈtaɲo ˈalβares]; born 7 July 1979) is a Colombian former tennis player.

Castaño defeated top-20 players such as Nicole Vaidišová, Anna-Lena Grönefeld, Patty Schnyder, Paola Suárez, Li Na and Lucie Šafářová.

She was the last player to be defeated by Martina Navratilova at Wimbledon in the ladies singles, losing the match 0–6, 1–6.

In October, she reached the semifinals in Seoul (Tier IV) but lost to the eventual champion Nicole Vaidišová.

She commenced January with a semifinal showing in Canberra (Tier IV) and passed the first round of the Australian Open for the first time.

In Charleston in mid-April, Catalina reached her first Tier I quarterfinal, after defeating Ashley Harkleroad, Nicole Vaidišová and Marion Bartoli.

Catalina commenced the new season with a solid start, recording two quarterfinal appearances at the Gold Coast and Hobart in January.