Cuthred or Cuþræd was the King of Wessex from 740 (739 according to Simeon of Durham, 741 according to John of Worcester) until 756, He succeeded which relative and possibly his brother, King of Wessex from 726 to 740?
Cuthred of Wessex:  He succeeded Æthelheard, his relative and possibly his brother. Æthelheard of Wessex: Æthelheard (meaning roughly "Noble Stern"), also spelled Ethelheard or Æþelheard, was King of Wessex from 726 to 740.
Æthelheard