(Swedish proper name, literal meaning: "Night and Day")
Swedish noble family, dating from the 13th century or earlier, but still extant. The family name, which has been in use since the 18th century, derives from the family's coat of arms, which is blazoned "party or et azure", i.e. gold/yellow and blue.
The most famous branch of the Natt och Dag family used the surname Sture. There have been several noble families in the Nordic countries to have used the Sture name, however, so not every Sture is of the Natt och Dag family.