Robert W. Niedermayer, Jr. (born December 28, 1974) is a Canadian professional ice hockey player currently playing for the Anaheim Ducks of the National Hockey League (NHL). He is the younger brother of fellow Ducks defenceman Scott Niedermayer and cousin of Edmonton Oilers defenceman Jason Strudwick.

Niedermayer was drafted 5th overall by the Florida Panthers in the 1993 NHL Entry Draft. At the time he was playing for the Medicine Hat Tigers of the Western Hockey League (WHL). He started his NHL career right away, without playing a game in the minors. During the 1996 NHL season he set career highs in goals, assists, and points in the regular season. In the playoffs, the Panthers went on an improbable playoff drive to the Stanley Cup Finals, before being swept in four games by the Colorado Avalanche. Niedermayer was hurt by concussions in the next years and has never been able to achieve the same level of scoring ability again. His NHL role soon turned into a defensive forward.

On July 23, 2001, Niedermayer was traded from the Florida Panthers to the Calgary Flames with a draft pick for Valeri Bure and Jason Wiemer. He did not last long in Calgary, and at the 2003 trading deadline he was traded to the Mighty Ducks of Anaheim. That same year he helped the Anaheim Ducks make an improbable run to the Stanley Cup Finals, his second such run. But again, Niedermayer's team lost, although this time it was in seven games to his brother's team, the New Jersey Devils.