Tuesday
Tuesday was named after the red planet, Mars. The Greek, Roman, Germanic, and Norse cultures all named the planet after their God of War. In Roman, Tuesday was "dies Martis", meaning "Day of Mars". The English name originated from the Norse God of War, "Tyr" from Viking mythology which evolved into "Tuesday".
Fun Fact: In Latin, Tuesday was called Martis dies, so Romance languages usually have similar names for Tuesday. It is called "mardi" in French, "martes" in Spanish, and "martedi" in Italian.