Catalina Castaño Álvarez (Latin American Spanish: [kataˈlina kasˈtaɲo ˈalβares]; born 7 July 1979) is a Colombian former tennis player. Her highest singles ranking is world No. 35 which she achieved July 2006.

In her career, she won ten titles on the ITF Women's Circuit, six in singles and four in doubles, as well as one doubles title on both the WTA Tour and Challenger Tour.

Castaño defeated top-20 players such as Nicole Vaidišová, Anna-Lena Grönefeld, Patty Schnyder, Paola Suárez, Li Na and Lucie Šafářová. She was coached by Peruvian-born British citizen Pablo Giacopelli since 2004.

In 1999 she won her first ITF title in Santiago. The following year she won two ITF titles in Midlothian and Cali. In 2001, she reached the quarterfinals in her home tournament of Bogotá, Colombia (Tier III). In 2002, Castaño advanced the semifinals in Bogotá. She reached four ITF finals, winning two of them - in Gorizia and Campobasso. She won 39 matches in the year and lost 18. In 2004, she reached the quarterfinals in Bogotá for the third time. She was the last player to be defeated by Martina Navratilova at Wimbledon in the ladies singles, losing the match 0–6, 1–6. She won her sixth ITF title in Orbetello.

In April, she won five matches in Miami (Tier I) including back-to-back wins over world No. 19, Paola Suárez, and world No. 13, Patty Schnyder, before falling to world No. 9, Venus Williams, in three sets in the round of 16. In May, she won four matches in Rome (Tier I) before losing to world No. 10, Vera Zvonareva, in the round of 16. In August, she reached her first ever WTA Tour final in Budapest. She lost to the top seed Anna Smashnova in the final, in straight sets. 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. Her two-sets win over Vaidišová, who was ranked 14 at the time, was her best win of the year. The following week in Berlin, Catalina beat Anna-Lena Grönefeld, who was ranked 14 at the time. It was her second win over a top-15 player in as many weeks. In May, she reached the quarterfinals in Istanbul (Tier III) for the first time. She reached her highest ranking of No. 35 on July 16.

Catalina commenced the new season with a solid start, recording two quarterfinal appearances at the Gold Coast and Hobart in January. At the Gold Coast, she defeated Li Na who was ranked 21 at the time.

Castaño retired from professional tennis after a diagnosis of breast cancer.

Outcome	Date	Tournament	Tier	Surface	Opponent	Score
Runner-up	Jul 2005	Budapest Grand Prix, Hungary	Tier IV	Clay	Anna Smashnova	2–6, 2–6

Outcome	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Winner	Jul 2012	Swedish Open, Båstad	International	Clay	Mariana Duque Mariño	Eva Hrdinová Mervana Jugić-Salkić	4–6, 7–5, [10–5]
Runner-up	Mar 2013	Mexican Open, Acapulco	International	Clay	Mariana Duque Mariño	Lourdes Domínguez Lino Arantxa Parra Santonja	4–6, 6–7(1–7)

Result	Date	Tournament	Surface	Opponent	Score
Loss	Feb 2013	Copa Bionaire Cali, Colombia	Clay	Lara Arruabarrena	3–6, 2–6

Result	Date	Tournament	Surface	Partner	Opponents	Score
Win	Feb 2013	Copa Bionaire, Colombia	Clay	Mariana Duque Mariño	Florencia Molinero Teliana Pereira	3–6, 6–1, [10–5]

Result	No.	Date	Tournament	Surface	Opponent	Score
Win	1.	29 March 1999	ITF Santiago, Chile	Clay	María Fernanda Landa	6–4, 6–2
Loss	1.	18 October 1999	ITF Nashville, United States	Hard	Florencia Labat	1–6, 1–6
Win	2.	8 May 2000	ITF Midlothian, Canada	Clay	Evelyn Fauth	6–3, 7–5
Loss	2.	23 April 2000	ITF San Luis Potosí, Mexico	Clay	Milagros Sequera	4–6, 6–3, 5–7
Loss	3.	13 November 2000	ITF Naples, United States	Clay	Yvette Basting	0–4, 0–4, 2–4
Win	3.	10 December 2000	ITF Bogotá, Colombia	Clay	Fabiola Zuluaga	4–1 ret.
Loss	4.	14 October 2001	ITF Hallandale Beach, United States	Clay	Fabiola Zuluaga	6–3, 3–6, 4–3 ret.
Win	4.	1 June 2003	ITF Campobasso, Italy	Clay	Nina Bratchikova	6–2, 6–2
Loss	5.	9 June 2003	Grado Tennis Cup, Italy	Clay	Martina Suchá	1–6, 2–6
Win	5.	16 June 2003	ITF Gorizia, Italy	Clay	Michaela Paštiková	7–6(2), 6–4
Runner-up	6.	1 September 2003	ITF Fano, Italy	Clay	Cristina Torrens Valero	3–6, 7–5, 3–6
Win	6.	29 June 2004	ITF Orbetello, Italy	Clay	Alona Bondarenko	2–6, 6–2, 6–3
Loss	7.	24 June 2012	Open de Montpellier, France	Clay	Séverine Beltrame	2–6, 6–7(4)

Result	No.	Date	Tournament	Surface	Partner	Opponents	Score
Loss	1.	14 September 1998	ITF La Paz, Bolivia	Clay	Carolina Mayorga	Laura Bernal Daniela Olivera	5–7, 7–6(5), 1–6
Win	1.	24 January 2011	ITF Bucaramanga, Colombia	Clay	Viky Núñez Fuentes	Nathália Rossi Zuzana Zlochová	7–6(3), 6–1
Loss	2.	25 July 2011	ITF Bad Saulgau, Germany	Clay	Mariana Duque Mariño	Maria Abramović Nicole Clerico	3–6, 7–5, [7–10]
Win	2.	17 January 2012	ITF Plantation, United States	Clay	Laura Thorpe	Jessica Pegula Ahsha Rolle	6–4, 6–2
Win	3.	22 October 2012	Internationaux de Poitiers, France	Hard	Mervana Jugić-Salkić	Stéphanie Foretz Gacon Tatjana Maria	6–4, 5–7, [10–4]
Win	4.	29 October 2012	Open Nantes Atlantique, France	Hard	Mervana Jugić-Salkić	Petra Cetkovská Renata Voráčová	6–4, 6–4
Loss	3.	12 May 2013	Open de Cagnes-sur-Mer, France	Clay	Teliana Pereira	Vania King Arantxa Rus	6–4, 5–7, [8–10]

Players who have been ranked world No. 1 are in boldface.

• Martina Navratilova - 0–1
• Nadia Petrova - 0–1
• Serena Williams - 0–1

• Catalina Castaño at the Women's Tennis Association
• Catalina Castaño at the International Tennis Federation
• Catalina Castaño at the Billie Jean King Cup (archived)