Gustav "Justav" Jaenecke (Born May 22, 1908 in Berlin, German Empire – Died May 30, 1985 in Bonn, West Germany) was a German ice Hockey player.

In 1928 he participated with the German ice Hockey team, in the Winter Olympics ice Hockey tournament.

The World Championships staged in 1930. Germany defeated all four of its continental opponents to claim the European title also on offer and, despite the 6-1 loss to Canada, earned the very first set of silver medals ever presented by the International Ice Hockey Federation (this is still the highest finish for Germany at a major international ice Hockey tournament). Jaenecke scored 9 goals in the tournament.

At the 1932 Winter Olympics in Lake Placid, New York, Jaenecke played in all six games for Germany, scoring only 1 goal. Germany would win the Bronze Medal - Because of the Great Depression only four nations fielded teams at Lake Placid.

In the 1933 World Ice Hockey Championships he scored two goals in a round robin match against Poland in Group B of the European tournament draw.

In the 1935 World Ice Hockey Championships in Davos, Switzerland he scored two goals against Poland in the ninth place game of the tournament.

At the 1936 Winter Olympic ice Hockey tournament he played all six matches and scored three goals. His teammate Rudi Ball was half-Jewish, and thus was initially overlooked for selection in the German ice Hockey team. Jaenecke, his good friend refused to play unless Ball was included. With much controversy Ball was finally included in the German team to play at the 1936 Olympic games.

Gustav Jaenecke was inducted into the International Ice Hockey Federation Hall of Fame in 1998.