Osmund of Sussex
He issued a charter, dated 762 in error for 765, as Osmundus.
He also issued a charter dated 770 in which he is listed as Osmundus rex.
So Osmund’s reign was from in or before 760 to between 770 and 772, as he witnessed a charter of Offa, King of Mercia, dated 772 as Osmund dux. Evidently he was demoted from king to ealdorman following Offa's conquest of Sussex.