Marcel Siem (born 15 July 1980) is a German professional golfer who plays on the European Tour where he has six victories.

In March 2013, Siem won for the third time on the European Tour at the Trophée Hassan II in Morocco.

[4] In November 2014, Siem claimed victory at the BMW Masters, the first event of the Race to Dubai finals series and his fourth overall on the European Tour.

He won in a sudden death playoff over Ross Fisher and Alexander Lévy with a birdie on the first extra hole.

[7] In February 2023, he ended an eight-year winless drought at the Hero Indian Open in his 501st European Tour start.