Helmer Julius Hanssen (24 September 1870 – 2 August 1956) was a Norwegian polar explorer, and one of the first five to reach the South Pole on the expedition of Roald Amundsen.

Helmer Hanssen was born in Bjørnskinn, on the island of Andøya in the northern part of Norway. He was an experienced ice pilot, a skill he had learned while hunting seals around Spitsbergen.

From 1903 to 1905 Helmer Hanssen participated in Roald Amundsen's successful search for the Northwest Passage, as second mate on board the ship Gjøa. On the expedition he learned from the Inuit how to drive sled dogs. In 1910 he headed south with Amundsen to conquer the South Pole. This time as an expert dog driver. He was also in charge of navigation, carrying the master compass on his sledge.

He was one of the first five people to reach the South Pole on 14 December 1911, along with Roald Amundsen, Olav Bjaaland, Oscar Wisting, and Sverre Hassel. During their stay at the South Pole, it is believed that Hanssen passed within 200 yards (180 meters) of the mathematical South Pole point. This was during one of his ski runs which Amundsen had ordered be performed to completely encircle or "box" the pole to ensure that there was no doubt that the expedition had attained the pole. For his participation in the expedition, he was awarded the Medal of the South Pole (Sydpolsmedaljen), the Royal Norwegian award instituted by King Haakon V in 1912 to reward participants in Roald Amundsen's South Pole expedition.