Godspeed You! Black Emperor were always scrupulous in protecting their identities and preventing their faces from becoming widely known - an approach shared by one of their collaborators, artist Will Schaff, who doesn't shun press interviews (like this one with Noisey) but does insist on wearing a mask for the occasion: "I feel that knowing what I look like becomes a distraction from my work, especially in today's world of social media."
Schaff is arguably best known for the sinister drawings that adorn the cover of Godspeed!'s Lift Your Skinny Fists Like Antennas To Heaven - still their finest LP, in my view - but he has a long-standing relationship with Okkervil River and has also produced cover art for Songs: Ohia and Jason Molina.
Not mentioned in Graham Isador's interview are his drawings for The West Is The Future, the 2004 album by one-time Low proteges Kid Dakota. Given the obscurity of the band, that's hardly surprising - but I do think that that artwork (a different picture to accompany each set of song lyrics) is the best of the lot.
(Thanks to Richard for the link.)