I hope the original uploader doesn't mind, but I replaced the "Chaos Space Marine' tag with 'Adeptus Astartes' and 'Black Templar' tags; I think that's an Iron Halo on his back, not a star of Chaos, and the pauldron symbol combined with the purity seals leads me to believe that he's still uncorrupted (at least, for now).

EDIT: Yup, Black Templar (Marshal Helbrecht, no less!)
https://www.reddit.com/r/ImaginaryWarhammer/comments/157iqdh/marshal_hubrecht_faces_the_hexwyrm_of_tlalokkan/