Ronny Ackermann (; born 16 May 1977 in Bad Salzungen, Bezirk Suhl) is a German former Nordic combined skier.
Ackermann started to learn to ski when he was five years old and took up ski-jumping two years later. As of 2004, he belongs to the team of Rhöner WSV Dermbach. His many successes include winning the Nordic combined World Cup in 2002, 2003 and 2008.
Ackermann found success in the FIS Nordic World Ski Championships, winning ten medals, including four golds (15 km individual: 2003, 2005, 2007; 7.5 km sprint: 2005), five silvers (7.5 km sprint: 2003, 4 x 5 km team: 2003, 2005, 2007, 2009), and a bronze (7.5 km sprint: 2001.) He also has won three silvers at the Winter Olympics in the sprint (2002) and team (2002, 2006) events. Ackermann is the first person to win the 15 km individual World Championships three straight times and the first to do it at the World Championships or Winter Olympic level since fellow German Ulrich Wehling did it during the Winter Olympics of 1972, 1976, 1980.
Ackermann has also won the Nordic combined event at the Holmenkollen ski festival three times, with 2 wins in the individual competition (2002, 2004) and a win in the sprint competition (2003). In 2003, Ackermann received the Holmenkollen medal (shared with Felix Gottwald).
He was elected Sportler des Jahres (Sportsman of the Year) in 2005.