One of the more underrated toy lines is the Fewture Devilman series. It never really achieved commercial success in North America, most likely due to poor marketing. But these figures boast some of the best sculpting in the industry with works by Yuji Oniki, and of course, Nirasawa, the master.
With each new series released, the demons & devils they made just got sicker and more beautiful to behold. And each figure would feature at least 4 different variants (colorwise) with cool names like "666 Ghost Glow" for the glow-in-the-dark variant, "Night Damned" for a transparent starry purple variant, or "Dragon Kind" for a red/green variant, etc.
Nirasawa's book Devilman: The List documents all the variants (plus custom variants by the sculptor!) in colorful detail. Fans of his work might also enjoy his Creature Core book - a collection of his model kits. Sick, otherworldly and glam-goth.
These days, many of the Devilman figures are easy & inexpensive to come by, and make excellent parts for customizing. cue evil laughter....
In the Devilman story, Zann was one of the grand demon lords of the underworld and commanded legions of monsters to do battle against Devilman. This is a re-paint version with re-sculpted open hands - the original figure had fists. It has been renamed the "Legendary Overfiend" variant.
Thanks for looking!