Carlos Arecio Amarilla Demarqui (born October 26, 1970) is a football referee from Paraguay. Amarilla has been a referee since 1997 and his first international game was between Uruguay and Ecuador. In the 2006 FIFA World Cup he took charge of the opening Group E match between the United States and the Czech Republic, and the Group G match between Switzerland and Togo.
His work in the second half of the crucial Group H match between Ukraine and Tunisia was publicly criticized. Amarilla was not chosen to officiate Knockout Round matches.
He was the referee in the first qualifying match for the 2010 World Cup between Colombia and Brazil (October 14, 2007).
He was preselected as a referee for the 2010 FIFA World Cup. Amarilla was chosen to officiate at the finals, but was withdrawn following the failure of a fitness test by his assistant referees.
On September 11, 2012, he officiated a 2014 FIFA World Cup qualifying match between Uruguay and Ecuador. He was heavily criticized after not giving a clear penalty to Ecuador.
Besides being a FIFA referee, Amarilla is an electrical engineer by trade.