Altariel is the pseudonym of British tie-in writer Una McCormack. As Altariel, she has written extensively in Tolkien fandom; she founded the Henneth Annûn mailing list, and was a co-founder of the Henneth Annûn Story Archive. She and her co-writer Isabeau of Greenlea have written an extended series of interconnected stories set in Gondor. Under her own name, she has written fanfiction based on Blake's 7 and Star Trek/Deep Space Nine.
See The Best of Trek Fanfic Interview with Una McCormack.