Nicholas Araújo Dias dos Santos (born 14 February 1980) is a former Brazilian competitive swimmer who specializes in freestyle and butterfly sprint events.

[20] In 10 May 2009, he broke the South American record in the 4 × 100-metre freestyle, with a time of 3:14.45, along with Nicolas Oliveira, César Cielo, and Fernando Silva.

[30] In August 2010, at the 2010 Pan Pacific Swimming Championships in Irvine, California, United States, Nicholas earned the silver medal in 50-metre butterfly.

[32] In December 2010, at the 2010 FINA World Swimming Championships (25 m) in Dubai, Nicholas Santos, along with César Cielo, Marcelo Chierighini, and Nicolas Oliveira, won the bronze medal in the 4 × 100-metre freestyle with a time of 3:05.74, South American record, leaving behind the American team.

[37] At the 2013 World Aquatics Championships in Barcelona, Santos qualified to the 50-metre butterfly finals in the first place, with a time of 22.81 seconds.

[41] At the 2013 FINA Swimming World Cup in Beijing, China, Santos broke the short-course South American record in the 50-metre butterfly, with a time of 22.13.

[42] At the 2014 Pan Pacific Swimming Championships in Gold Coast, Queensland, Australia, he finished 8th in the 100-metre butterfly, and 16th in the 50-metre freestyle.

[43] At the 2014 FINA World Swimming Championships (25 m) in Doha, Qatar, Santos won two gold medals on the same day.

At 4 December, in the Men's 4 × 50 metre medley relay, formed by Santos, César Cielo, Felipe França Silva and Guilherme Guido, considered the "Dream Team" by Cielo (formed only by medalists or world champions in their respective individual events), Brazil won the gold shattering the world record with a time of 1:30.51.

[53] At the 2016 FINA World Swimming Championships (25 m) in Windsor, Ontario, Canada, he won a silver medal at the 4 × 50 metre mixed medley relay, along with Etiene Medeiros, Larissa Oliveira and Felipe Lima.

[57] At the 2017 World Aquatics Championships in Budapest, in the Men's 50 metre butterfly, he won again the silver medal, with a time of 22.79.

[60] He also won a bronze medal in the Men's 4 × 50 metre medley relay, along with Guilherme Guido, Felipe Lima and César Cielo.

[63] At the age of 39, at the FINA Champions Swim Series held in May 2019 in Budapest, he was able to beat the Americas record in the 50m butterfly, with a time of 22.60.

[65][66] At the 2021 FINA World Swimming Championships (25 m) in Abu Dhabi, United Arab Emirates, in the Men's 50 metre butterfly, Santos won the gold medal with a time of 21.93.