Astrape, Greek goddess of lightning, handmaiden of Zeus.
Philostratus the Elder, Imagines 1. 14 (trans. Fairbanks) (Greek rhetorician C3rd A.D.) :
[From a description of an ancient Greek painting depicting the death of Semele :]
"Bronte (Thunder), stern of face, and Astrape (Lightning), flashing light from her eyes, and raging fire from heaven that has laid hold of a king’s house, suggest the following tale, if it is one you know. A cloud of fire encompassing Thebes breaks into the dwelling of Kadmos as Zeus comes wooing Semele; and Semele apparently is destroyed, but Dionysos is born, by Zeus, so I believe, in the presence of the fire."
In the Apulian vase painting below, Astrape (labelled) stands beside the throne of Zeus bearing the armaments of the sky-god. She also wields a torch and is a crowned with a shining aureole.
(From here: http://www.theoi.com/Titan/Astrape.html )