Comments made to our Dark Souls Wiki
Dank Iron D a n k u s s
Tarkus is actually implied to still be human. (Or as close to human the strongest warrior in the series is, yes he beat Havel as implied by having his ring) Also he most likely went into the painted world and succumbed to his injuries after leaving. (Considering there's a Berenike knight in the painted world it makes more sense than dying on a lesser version of some of Sen's Fortress).
If it looks like chicken, smells like chicken, tastes like chicken but iron tarkus says it's beef. It's beef
Tarkus never died. He just found Anor Londo too easy, so he took off all his equipment and soloed the place naked.