Alejandro Castellanos (born August 29, 1979) is a Honduran former swimmer who specialized in sprint freestyle events.

[1] Castellanos represented Honduras at the 2000 Summer Olympics, where he became the nation's flag bearer in the opening ceremony.

Castellanos competed only in the men's 100 m freestyle at the 2000 Summer Olympics in Sydney.

[3] He challenged seven other swimmers in heat three, including Trinidad and Tobago's 16-year-old George Bovell and Seychelles' three-time Olympian Kenny Roberts.

Castellanos failed to advance into the semifinals, as he placed sixty-fourth overall in the prelims.