Óscar Julián Ruiz Acosta is a former Colombian football referee and current referee instructor. He is also a lawyer.
He had been a referee since 1 January 1995, and his international debut was on 12 July 1995 (Paraguay vs. Venezuela). He officiated in the 2002, 2006 and 2010 FIFA World Cups.
FIFA appointed Ruiz as a referee instructor and member of CONMEBOL's referee assistance program.