Sandman is the main antagonist and title character of the 1991 horror stop-motion short by Paul Berry (which was nominated for the Academy Award for Best Short Film).
Regarding the villain wars, Sandman plays a minor role in Non-Disney Villains Tournament, being a corrupted version of the Rise of the Guardians version of Sandman and acting as a henchman for Pitch Black.
Non-Disney Villains Tournament
A Miser Brother's Nightmare
The Miser Brothers are quickly taken care of by Sandman, sent by Pitch Black, seeing as Pitch Black wanted no loose strings left after Zeebad's failure. Brutally and efficiently, the Sandman gouges the Miser Brother's eyes out before feeding them to his deformed "chicks".
Ever connected to Pitch Black; when the Boogeyman went missing in action after facing the Mysterious Stranger, Sandman quickly followed to where the masked creature was, attacking him in order to gain some form of retribution. His efforts were futile however, as the Stranger quickly retaliated. Oddly enough, in an act of mercy, the masked creature restored Sandman to his pure and heroic self.
A perplexed and lost Sandy stood by confused as the Stranger rambled on his intentions to rebuild the world in his own image.