Kathe Koja (born 1960) is an American writer. She was initially known for her intense speculative fiction for adults, but over the past few years has turned to writing young adult novels.
Koja is also a prolific author of short stories, including many in collaboration with Barry N. Malzberg. Most of her short fiction remains uncollected. Koja's novels and short stories frequently concern characters who have been in some way marginalized by society, often focusing on the transcendence and/or disintegration which proceeds from this social isolation (as in The Cipher, Bad Brains, "Teratisms," The Blue Mirror, etc.). Koja won the Bram Stoker Award and the Locus Award for her first novel The Cipher, and a Deathrealm Award for Strange Angels. Her prose has been described as "stunning".