Márcio Nuno Ornelas Abreu (born 25 April 1980) is a Portuguese former professional footballer who played as a winger.

Marítimo, and going on to represent its every youth sides, Abreu never settled in the first team, constantly bouncing between that squad and the reserves.

In 2004, he was released and joined Madeira neighbours A.D. Camacha in the third division, the same as Marítimo B. Abreu signed in the summer of 2007 with Bulgarian club PSFC Chernomorets Burgas, being regularly used during his three-and-a-half-season spell.

In February 2011 he was transferred to Russia's FC Krasnodar, freshly promoted to the Premier League.

On 6 February 2011, Abreu participated in his first game for his new team, playing the first 72 minutes in the 2–2 friendly draw with Ukraine's SC Tavriya Simferopol.