Shax is a male demon.
A shapeshifting demon who, when in the mortal realm, takes the form of a birdlike shadow monster, Shax admires power but is grumpy if he is summoned twice in too short a timespan, and can only be contained inside a magic triangle. In "private" in Hell, he is also a bit of a scatterbrain, forgetting to pay his taxes and such. Shax appears not to get along with fellow demon Andras.
Shax was summoned in 2017 by sorceress Magica De Spell as part of a scheme to get the Number One Dime. In the aftermath, Magica, protecting herself by exploiting the luck of Gladstone Gander, managed to jinx Shax, cursing him with terrible bad luck; Shax agreed to let Magica go in exchange for her letting him go free and jinx-less, but not before his bad luck had resulted in his somehow getting fired from Hell (in part due to having forgotten to pay his taxes as earlier mentioned).
Behind the scenes
This version of the demon Shax was first seen in 2017 in A Kind of Magic.