An ONI Artificial intelligence construct, Beowulf was the attaché to Admiral Michael Stanforth and the UNSC Navy.
He was present during the SPARTAN's original briefing about the Covenant Empire.
He was later assigned to guard the UNSC personnel and planning database. He knew Cortana well and knew that she was trouble. When she would try to get into the system, he would block her entrance.
He was thorough, methodical and paranoid. However, Cortana quickly cracked her way around his defenses to access John-117's CSV. He was incapable of learning, due to the fact he was a "dumb" AI.
His holographic appearance was that of a man wearing a hooded cloak.
- Beowulf was named after the titular character of the famous heroic poem Beowulf, the only surviving piece of ancient Anglo-Saxon heroic poetry.