What kind of English was Beowulf written in?

Beowulf was written in Old English, also known as Anglo-Saxon. It's a language that is no longer spoken, but it's the ancestor of modern English. Old English was heavily influenced by the Germanic languages spoken by the Anglo-Saxon tribes who settled in Britain.

Here's a fun fact: While it's considered a "dead" language, Old English is still studied by academics and enthusiasts, and some people even try to learn it as a hobby.