Katrin Holtwick (born 10 April 1984) is a German retired beach volleyball player. From 2006 to 2016, she played with Ilka Semmler. They competed at the 2012 Summer Olympics in London.
She won 2 gold medals, 5 silver medals and 6 bronze medals in the FIVB Beach Volleyball World Tour.
At the 2016 Grand Slam in Long Beach, California (Germany vs Germany) the pair finished 4th after a loss to their compatriots Chantal Laboureur/Julia Sude in straight sets (21-16, 21-17).
In September 2016 Holtwick retired after two losses in the German Beach Volleyball Championship.