Conversation so far:
what is Thomas Malory's identity
Malory’s identity has never been confirmed, but the likeliest candidate is Sir Thomas Malory of Newbold Revel in Warwickshire.
how is Thomas Malory described
He is described as a knyght presoner, distinguishing him from the other six individuals also bearing the name Thomas Malory in the 15th century when Le Morte d'Arthur was written.

Question: did he write anything else
Self-contained rewrite: did Thomas Malory write anything else