|Race||Dark Iron dwarf (Humanoid)|
|Location||Lightning Ledge, Mount Hyjal|
He is best known for his discovery of "Electra-atrocity", a powerful elemental substance, created within the swirling currents of air elementals. It can be used for various purposes, one of which is to maintain the Elemental Planes' portals without the constant need of channeling by the summoners. He described his findings in the book The Condensation of Electra-Atrocity.
- You're interrupting work your feeble mind cannot possibly comprehend!
- Leyden's Cooperkleist's name might be a tribute to Pieter van Musschenbroek of Leiden and Ewald Georg von Kleist, both who have invented device called Leyden/Kleist jar, which is used to store static electricity, in similar fashion to the Copperkleist's device.
- He is most likely a former servant of late Emperor Dagran Thaurissan.
- He may be considered an elementalist.
- Patch 4.0.3a (2010-11-23): Added.