Marián Olejník (born 1976) is ánOlejnía Slovak slalom canoeist who competed at the international level from 1993 to 2007, specializing in the C2 event.
He and his partner in the boat Milan Kubáň won three medals at the ICF Canoe Slalom World Championships with two silvers (C2: 2005, C2 team: 1999) and a bronze (C2 team: 2006). The silver medal in the C2 event at the 2005 World Championships in Penrith was their greatest achievement.
At the European Championships Kubáň and Olejník won a total of 5 medals (2 golds, 1 silver and 2 bronzes), including a bronze medal in the C2 event at the 1998 European Championships in Roudnice nad Labem. The remaining four medals have come from team events.
They have earned a total of eight World Cup podiums, including 4 wins.