Oslac was a King of Sussex

Kingdom of Sussex

The Kingdom of Sussex or Kingdom of the South Saxons was a Saxon colony and later independent kingdom of the Saxons, on the south coast of England. Its boundaries coincided in general with those of the earlier kingdom of the Regnenses and the later county of Sussex. A large part of its territory...

. He reigned jointly with Ealdwulf

Ealdwulf of Sussex

Ealdwulf was a King of Sussex, but is known only from his charters. He reigned jointly with Ælfwald and Oslac.Ealdwulf issued an undated charter, believed to be from about 765, as Alduulf rex ....

 and Ælfwald

Aelfwald of Sussex

Ælfwald was a King of Sussex, who reigned jointly with Ealdwulf and Oslac, and probably also with Oswald and Osmund.Ælfwald witnessed an undated charter of Ealdwulf, believed to be from about 765, with his name corruptly recorded as Ælhuuald rex....

, and probably also Oswald

Oswald of Sussex

Oswald was an Ealdorman of Sussex, jointly with three former kings: Osmund, Ælfwald, and Oslac.He witnessed a charter of Offa, King of Mercia, dated 772 as Osuualdus dux Suðsax . He was listed ahead of the three former kings Osmund, Ælfwald, and Oslac, which implies that his rank was higher. It is...

 and Osmund

Osmund of Sussex

Osmund was a King of Sussex, apparently reigning jointly with Oswald, Ælfwald, and Oslac.According to the Anglo-Saxon Chronicle, version D, Osmund was reigning in Sussex when Archbishop Cuðberht died in 760, so his rule commenced before that event.He issued a charter, dated 762 in error for 765,...

.

Oslac witnessed an undated charter of Ealdwulf, believed to be from about 765

765

Year 765 was a common year starting on Tuesday of the Julian calendar. The denomination 765 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.-Africa:* The Zenete Berber tribe of Banû Ifrân rebels...

, with his name corruptly recorded in the surviving revision as Osiai rex http://www.anglo-saxons.net/hwaet/?do=seek&query=S+50.

After the conquest of Sussex by Offa

Offa of Mercia

Offa was the King of Mercia from 757 until his death in July 796. The son of Thingfrith and a descendant of Eowa, Offa came to the throne after a period of civil war following the assassination of Æthelbald after defeating the other claimant Beornred. In the early years of Offa's reign it is likely...

, King of Mercia, Oslac witnessed a charter of Offa, dated 772

772

Year 772 was a leap year starting on Wednesday of the Julian calendar. The denomination 772 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.- Europe :* Frankish king Charlemagne starts fighting...

, as Oslac dux http://www.anglo-saxons.net/hwaet/?do=seek&query=S+108, with his name placed after Oswald, Osmund, and Ælfwald, suggesting that he was the most junior of the former kings.

His latest surviving charter is dated 780

780

Year 780 was a leap year starting on Saturday of the Julian calendar. The denomination 780 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.- Byzantine Empire :* Constantine VI becomes Byzantine...

, and the original still exists; in it he is styled Oslac dux Suthsaxorum http://www.anglo-saxons.net/hwaet/?do=seek&query=S+1184.