Kos

Kos is the chaotic god of the Rogue pantheon.

Encyclopedia entry

"I am not a coward!" he cried.  "I'll dare Thieves' House
and fetch you Krovas' head and toss it with blood a-drip at
Vlana's feet.  I swear that, witness me, Kos the god of
dooms, by the brown bones of Nalgron my father and by his
sword Graywand here at my side!"
   [ Swords and Deviltry, by Fritz Leiber ]