Gastón Norberto Gaudio (born December 9, 1978 in Temperley, Buenos Aires), nicknamed El Gato (The Cat in Spanish), is a professional tennis player from Argentina. His career-high ATP Entry ranking was No. 5 in 2005.

Gaudio is one of the most unpredictable players in the modern game, as he is capable of spectacular shotmaking especially with his outstanding single hand backhand and clever dropshots and within a short timeframe can self-destruct, which leaves himself and tennis fans in general frustrated with his inability to attain a level consistently enough and something that Gaudio acknowledges.