Argenis Casimiro Núñez (born December 30, 1981) is a Dominican amateur boxer best known for winning two medals at the Pan Am Games.

In 2003, at the Pan Am Games, he beat Washington Silva but lost to Cuban southpaw Yoan Pablo Hernández in the light-heavyweight category and won bronze.

At the Central American Games in 2006, he lost in the first round to eventual winner Yordanis Despaigne.

At the Pan Am Games in 2007, he won silver at middleweight, losing to Emilio Correa.

At the World Championships in 2007, he KO'd Elshod Rasulov and beat two other fighters but did not win a medal because he lost to Ukrainian Sergiy Derevyanchenko.