Sebastián Marcelo Blanco (born 15 March 1988) is an Argentine footballer. He currently plays as a midfielder for Portland Timbers in Major League Soccer.
Blanco made his breakthrough into the Lanús first team in 2006. In 2007, he was part of the squad that won the 2007 Apertura championship, the first top flight league title in the club's history. On 30 August 2014, Blanco signed a two-year contract with the option of a third year with Premier League side West Brom.
On 20 May 2009, Blanco made his debut for the Argentine national team in a friendly match against Panama, coming on as a second-half substitute.