Augusto Matías Fernández (Latin American Spanish: [awˈɣusto maˈti.as feɾˈnandes]; born 10 April 1986) is an Argentine former professional footballer who played as a central midfielder.

He started his club career in Argentina with River Plate, before moving to French club Saint-Étienne, and then back Argentina with Vélez Sarsfield. In 2012, he moved to Spain to play with Celta and then Atlético Madrid. In 2018, he joined Chinese club Beijing Renhe, before joining Cádiz in Spain where he retired in 2021.

He made his debut for Argentina football team in 2011. He played 16 times for his country, and represented them at the 2014 World Cup, where he won a runners-up medal, and at the 2016 Copa América.

Born in Pergamino, Buenos Aires, Fernández was a River Plate youth graduate. He made his first team debut on 29 January 2006, coming on as a substitute for Jonathan Santana in a 5–0 away routing of Tiro Federal.

Fernández scored his first professional goal on 8 April 2007, netting the equalizer in a 1–1 home draw against Belgrano. With River, he won the 2008 Clausura under Diego Simeone's coaching, playing on 15 of the 19 games (nine starts).

On 28 August 2009, after fellow Argentine Gonzalo Bergessio joined Saint-Étienne, Fernández arrived at the aforementioned French club. He was loaned to the French club by a third-party owner of his rights, Israeli businessman Pinhas Zahavi.

Fernández made his Ligue 1 debut on 13 September 2009, starting in a 0–1 loss to Rennes, and scored his first goal in the category roughly a month later in a 3–1 home win against Bordeaux. However, he only appeared in 12 matches during the campaign, as his side narrowly avoided relegation.

On 9 July 2010, Fernández signed a three-year deal with Argentine Primera División side Vélez Sarsfield, who bought 100% of his rights from Pinhas Zahavi for a fee of US$1.5 million. In his first tournament with his new club, the 2010 Apertura, he played 12 games (all as a starter) on Vélez' runner-up campaign.