Leyden Copperkleist[29.6, 40.4] is a dwarf named mob associated with the Twilight's Hammer clan located at the Lightning Ledge in Mount Hyjal.
- Leyden Copperkleist says: You're interrupting work your feeble mind cannot possibly comprehend!
- Leyden is presumably the author of the nearby book, The Condensation of Electra-Atrocity.
- He is named after the inventors of the Leyden jar, used to store electricity - Pieter van Musschenbroek of Leiden and Ewald Georg von Kleist - as well as a material that conducts electricity, copper.
- Patch 4.0.3a (2010-11-23): Added