Monday

This is also an African American name (as with all the other weekdays). Naming children after the day they were born is common in some African cultures, notably Akan. Early slaves in America continued the day-naming practice with the English equivalents. For this fascinating history, see http://slaverebellion.org/index.php?page=africanisms-in-names.

Yes, this was a real name. It was used in England during the Medieval era. It was not unusual for Christian families to name children after the day they were born if that day meant something in Christianity... be it Christmas, Easter, or even Monday. Mondays are the day after Sunday, so it's kinda special.