"Did you not recognize the creatures that moved in the shadows? The Apes too had served the Dark Master, but more for their own greed and thirst for power than any true loyalty to him. This is how Malefor repaid them... doomed to remain in the dark... feeding off the power of others, never being fulfilled."
The Hermit

The Shadow Apes are the dark remnants of the Apes in Dawn of the Dragon. According to the Hermit, although the Apes had served Malefor, they did so more for their ends than their true commitment to him. When Malefor returned, he cursed the Apes into shadows as payment for their disloyalty.

The Shadow Apes were first encountered at the Hermit's cave near the Valley of Avalar, where they ambushed Spyro and Cynder. After they were defeated, the Hermit explained to the young dragons that the creatures they defeated were, in fact, the Apes they faced three years prior, having been turned into ghostly skeletons for their disloyalty by Malefor. 

The Shadow Apes were later encountered in the Ruins of Warfang, where they dwelled and lurked within the shadows and holes of the ruins. Even though they are cursed, the Shadow Apes still proved themselves to be a nuisance, as one was seen pulling a switch that extended a wall that blocked Spyro and Cynder while they were making their way across the chasm in the Ruins, trying to prevent them from retrieving the red crystals used to open the gates to the Dragon City of Warfang. Another Shadow Ape later swiped a red crystal at an altar before Spyro and Cynder could reach it, before a horde of Shadow Apes appeared. If they killed that Ape and the red crystal hasn't been picked up, another Shadow Ape from the horde would swipe it and keep in its grasp until it is killed.