Sir Haedlac Galladon VII = "Gal-Pal" (of Petreus), "Gallon-dong"
The first one became such a meme in my tiny gaming group...
Ur-Khan = "Orc Norris"
Spawned countless "Orc Norris Facts"
Ischaldirh = "Bless you"
His name sounds vaguely like someone sneezing
Golgor Dhan = "Gol' Damn" - often said when sighting him for the first time in a game
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New versions, new uniques, new names:
High Lady Kauhistuttava = "Queen Kut-tut"
Lady Decora = "Decor-Thor"
Moryggan = "Moggy" (british slang for dog)
Efra Peredivall = "HEEP" (His Excellency Efra Peredival)