哈德克努特（Hardeknud，意为强壮的克努特；1018年－1042年6月8日），也被后世称为丹麦的克努特三世（Knud 3.）和英格兰的克努特二世（Canute II），是丹麦国王和英格兰国王，丹麦统治英格兰时代的末代君主。1035年，哈德克努特继承了其父，当上了丹麦国王，是为克努特三世。后来他于1040年亦当上了英格兰国王，称作克努特二世。1042年，哈德克努特于宴席上饮酒时暴毙，由忏悔者爱德华继位，丹麦王朝结束，威塞克斯王朝复辟。

Harthacnut, Harðacnut, or Canute III (Danish:Hardeknud; "Tough-knot"; c.1018 – 8 June 1042) was King of Denmark from 1035 to 1042 and King of England from 1040 to 1042.

He was the son of King Cnut the Great (who ruled Denmark, Norway, and England) and Emma of Normandy. When Cnut died in 1035, Harthacnut struggled to retain his father's possessions. Magnus I took control of Norway, but Harthacnut succeeded as King of Denmark and became King of England in 1040 after the death of his half-brother Harold Harefoot.