This is Jes Goodwin’s 1990 sculpt of a World Eater, which really set the mold for the aesthetic from then on. The earlier guys were much more… organic looking, and the Dave Andrews sculpts in the 1992 catalogue are more reminiscent of the earlier Rogue Trader sculpts than what came later.
He appears in White Dwarf 135 as “World Eater Space Marine of Khorne with Chainsword and Boltgun”:
Undercoat: Vallejo Mecha Black
Black: Kimera Phthalo Green mixed with The Red.
Red: Scale75 Burgundy Wine Red, then Primary Red/Crimson/Intense Yellow. Then shading with Sap Green and Kimera Ultramarine Blue, then tinted with Scalecolor Artist Red Ink and Yellow Ink diluted with Vallejo Airbrush Flow Improver.
Gold: Burnt Sienna Umber, Yellow Oxide and Intense Yellow, with a little bit of Pro Acryl Titanium White. Then I got the Kimera base set and tried mixing up a chromatic black out of The Red and Phthalo Green, a brown out of Phthalo Green and Red Oxide and then stippling a little Warm Yellow with edge highlighting of Cold Yellow and The White. Corrosion is Phthalo Green and then some Oxide Green + The White. Couldn’t nail the NMM, so I went back to Necro Gold + Elven Gold + Citrine Alchemy with Bold Titanium White highlights, washed with Scale Artist Chestnut Ink. Shaded with Kimera Phthalo Green.
Green: Kimera Cold Yellow (PY151 Benzimidazolone Yellow) mixed with Phthalo Blue Green Shade (Cu-Phthalo Blue).
Leather: Kimera The White, with Oxide Brown Light over that, shaded with Royal Brown, highlighted with a mix of Royal Brown and The White.
Silver: Black Metal, shaded with thinned Royal Brown, spots of rust with Mars Orange, highlights with Speed Metal.
Pigments: Vallejo Light Sienna and Titanium for the skulls. Rim in Vallejo Black Grey.