With the exception of Saturday, Sunday and Monday, the days of the week are named after Norse Gods:
Old English Sunnandæg meaning “Sun’s day”.
Old English Mōnandæg meaning “Moon’s day”.
Old English Tīwesdæg meaning “Tiw’s day”. Tiw (Týr in Norse) is a one-handed god associated with law and heroic glory.
Old English Wōdnesdæg meaning “Woden’s day”. Woden is also known as Odin and is often considered as the leader of the Norse gods. Often depicted as one-eyed and long-bearded he is father to Thor and husband to the goddess Frigg.
Old English Þūnresdæg meaning ‘Þunor’s day’. Þunor being thunder or its personification. In German, Thursday is “Donnestag” (thunder’s day).
As perhaps the most famous Norse God, Thor is the hammer-wielding god of thunder, resulting in “Thor’s day” in later English.
Old English Frīgedæg meaning “Frige’s (or Frigg’s) day”. Frige and Frigg (Odin’s wife) are not the same goddess and there is some debate as to which the day is named after. Freyja/Freya is another norse goddess to add to the confusion.
Old English Sæturnesdæg meaning “Saturn’s day” is the only day of the week to retain its Roman origin. Saturn being the Roman god of generation, dissolution, plenty, wealth, agriculture, periodic renewal and liberation.