Barry Mark Eisler (born 1964) is a best-selling American novelist. He is the author of two thriller series, the first featuring anti-hero John Rain, a half-Japanese, half-American former soldier turned freelance assassin, and a second featuring black ops soldier Ben Treven. Eisler also writes about politics and language on his blog Heart of the Matter, and at the blogs CHUD, Firedoglake, The Huffington Post, MichaelMoore.com, The Smirking Chimp, and Truthout.