Danish center best known to NHL fans for his years with the Montreal Canadiens, with whom he began playing in 2010. He previously played in the Swedish Hockey League and won gold medals representing Denmark at the IIHF World Under-18 Championship and World Junior Ice Hockey Championships in 2007.
He was born and raised in Rodovre, Denmark. He began playing for his hometown team, the Rodovre Mighty Bulls, in 2004.
In a January 2012 game against the Winnipeg Jets, he became the first Montreal Canadien to score four goals in a game since Jan Bulis did so in 2006.
His father is former hockey player and color commentator Olaf Eller. His brothers Michael and Mads have also played professional hockey.
He has played alongside American left winger Max Pacioretty in Montreal.