Alex Negrea is an artist who has done work for companies like Crytek and Volta. We've actually featured Alex's art previously: the Mercy piece here was commissioned by Blizzard, and ran in a best-of we made around the game's launch.
Yeah, the game itself has only just been released, but thanks to marketing and betas people have been getting to know the cast of Overwatch for months. Among those fans are some of the world's best artists, many of whom we've featured here on Fine Art before.
You can see more of Alex's work at his ArtStation page.