While there are a number of translations of Sir Gawain and the Green Knight, there are also many which are simply about the famous poem and it's unknown author, usually called "the Pearl Poet" or "the Gawain Poet."
About The Poem, Analysis and History
The Folio Society Edition 2016 - Translation and commentary
Translations of the Poem from Middle English into Modern tongue
Marie Borroff 1967 Sir Gawain and the Green Knight A New Verse Translation (Norton Anthology)
The Simon Armitage translation (includes the 1962 Everyman's Library version, too)