Ondrej Nemec (born 18 April 1984) is a Czech professional ice hockey defenceman who currently plays for Severstal Cherepovets of the Kontinental Hockey League (KHL).
He was selected by the Pittsburgh Penguins in the 2nd round (35th overall) of the 2002 NHL Entry Draft.
On 2 July 2014, Nemec left HC Lev Praha, after it declared bankruptcy and folded, as a free agent to sign with fellow KHL club, Atlant Moscow Oblast.