Helgi the Sharp (Old Norse: Helgi hvassi) was a legendary king of Zealand in the saga fragment Sögubrot af nokkrum fornkonungum. He was the co-ruler with his brother Hrà Ârekr.
Helgi visited the court of King Ivar in Sweden to ask for the hand of his daughter Aud. Although Aud was inclined to accept Helgi's offer, Ivar rejected it. Ivar told Helgi that while he (Ivar) was in favour of the match, Aud did not want him. Later, Helgi suggested that his younger brother Hrà Ârekr should seek Aud's hand, and Helgi returned to King Ivar to ask for her hand on his brother's behalf. Aud would rather not have accepted the offer, as this would have been further insult to Helgi, but Ivar overruled her decision and agreed the match, so Aud returned to Zealand with Helgi and married Hrà Ârekr. Some time later, once Hrà Ârekr and Aud's son Harald was born, Ivar visited Zealand and told Hrà Ârekr that Auðr was unfaithful with Helgi, and that people said Harald was Helgi's son. Hrà Ârekr then killed Helgi and after this Hrà Ârekr was himself soon killed by his father-in-law Ivar who had one opponent less and wanted to include Zealand in his dominions.