Ívarr inn víðfaðmi or Ivar Vidfamne was, according to legend, a king of Sweden 655-695, Norway, Denmark, and parts of England. He was the son of Halfdan the Kind of the house of Skjöldung (Scylding).

His story is related only by Icelandic sources, notably Snorri Sturluson, and he may be no more than a legend.

He began as king of Scania and conquered Sweden by defeating Ingjald Illråde. He is then said to have conquered all of Scandinavia and parts of England. Because of his harsh rule, many Swedes fled west and populated Wermelandia under its king Olof Trätälja.

His last campaign was in Russia where he died, defeated by Odin in disguise. (Another source claims he took his life by drowning himself in the Gulf of Finland.)