Gladys is a demon that transfers the souls that Sam captures with whichever vessel he is presented with; back to Hell, from her cubicle at DMV.
Throughout the series in season 1, Gladys has been known to appear in most episodes. After the WGOA strike, she had appeared in more then just the usual DMV scenes. The only times she misses work is for holidays, like Halloween, as seen in Leon.
In The Cop, Gladys is seen purchasing numerous household items, which leads Sock and Ben to investigate her house, were they find many un-demonic things, such as Angel Figurines and a greenhouse full of flowers. They discover that while Gladys may have a temper, she also has feelings.
In The Leak, Gladys repeatedly frees a captured soul, her motivation being that she feels loneley and the soul in question made her feel wanted. Eventually, Sam, Andi, and Sock track down the soul who proceeds to "kill" Gladys. Sam and his friends nearly bury Gladys alive until another demon, Tony, tells them that demons can't be killed by mortal weapons, and removes the blades, 'waking' Gladys up. After this, The Devil appears at the DMV and transfers Gladys back to Hell. She is brought back to the DMV at Sam's request, and has been working there since.
Gladys is not social, but takes a liking to Andi. Sock flirts with her constantly.