List of earls in the reign of King John
The following individuals were Earls (suo jure or jure uxoris) or Countesses (suo jure) during the reign of John, King of England who reigned from 1199 to 1216. The period of tenure as Earl or Countess is given after the name and title of each individual, including any period of minority.
Source: Wikipedia — List of earls in the reign of King John (CC BY-SA 4.0)