Rubén Felgaer (born 4 April 1981) is an Argentine chess player who received the FIDE title of Grandmaster (GM) in 2002.

Felgaer won the Pan American Junior Chess Championship in 2000 and 2001.

In 2001, he shared first at Mar del Plata and took 7th in Buenos Aires (14th Najdorf Memorial; Anatoly Karpov won).

In 2003, he tied for 2nd–9th in Lido degli Estensi (Artur Kogan won).

He participated in the FIDE World Chess Championship 2002 (knocked out in the first round by Loek van Wely) and in the FIDE World Chess Championship 2004 (knocked out in the second round by Alexey Dreev).