Carlos Alonso Farrenberg (born 10 January 1980) is a Paralympic swimmer from Brazil competing mainly in category S13 events for partially sighted athletes.

At University he took up goalball, but then heard of trials for disabled swimmers for the 2004 Summer Paralympics in Athens and decided to try out.

[3] Despite being away from the pool for ten years and with only a month of training, Farrenberg broke three Brazilian swimming records for the S13 class during the trails.

[3] He first represented Brazil at the 2006 IPC World Swimming Championships in Durban winning a silver medal in the 100 metre freestyle (S13).

[2] In the build-up to the 2016 Summer Paralympics in Brazil, he won a silver in the 50 metre S13 at the 2015 IPC Swimming World Championships in Glasgow.