The Dragonman is a scrapped enemy in Serious Sam: The First Encounter.
The Dragonman was supposed to be similar to the Scythian Witch-Harpy in that it flew and tossed projectiles. There were supposed to be three versions of the Dragonman: the Soldier, the Sergeant and the Monster. Each did the same amount of damage, but had increasing amounts of health.
The Dragonman appears to be have been based off of the Harpy's code, as the line “woman can't harm woman” (Woman being the internal name for the Harpy) appears in the Dragonman's code.
The Dragonman appears with the Harpy in pictures of an early version of Moon Mountains, showing that they were supposed to appear together.