Marius Achim Baciu (born 1 May 1975) is a Romanian former player and current football head coach.
Baciu started his career playing as a youth for Gaz Metan Mediaș, before joining the squad of FC Inter Sibiu as a professional player in 1992.
One year later he was loaned to his former team Gaz Metan Mediaș, rejoining FC Inter Sibiu in 1994.
In 1996, FC Inter Sibiu was relegated from Liga I, but Baciu, then 21, was signed by Steaua București winning the championship in 1997 and 1998 and the Cupa României in 1999.
In 2002, he left Steaua to play in France for Lille OSC but after two mediocre seasons he was released from his contract and signed with the German squad Rot-Weiß Oberhausen as a free agent.