Appendages (horns) – The being has horns. Horns are associated with beasts and worse, the devil so a character with horns is almost always a bad guy or struggling with an evil nature as is the case with Hellboy.
Bull Dog (DC) belongs to the Space Canine Patrol Agents has horns like a bull (Superboy V1 #131).
The Man-Bull (Marvel) first appears in Daredevil V1 #79.
El Toro (Marvel) puts a cap on with some horns and takes on Giant Man in Tales to Astonish V1 #54.
H. R. Costigan has horns (Love & Rockets – The Girl from H.O.P.P.E.R.S V2).
Hellboy’s (Dark Horse) horn growth are indicative of the degree that his demonic nature has taken over (Hellboy – Wake the Devil #5).
Kro (Marvel) grows some horns to look like the devil and manipulate humans in The Eternals V1 #3.
The Minotaur (Marvel) fights in the Invincible Iron Man V1 #24.
Devilina (Atlas-Seaboard) is not too happy with her new horns in Devilina #1.
The Overlord Karellen in Childhood’s End belongs to a race that resembles the devil. Our fear of the devil may be due to clairvoyance. Karellen as he appears in the TV miniseries.
Overlords in Barlowe’s Guide to Extraterrestrials.
The Rhino (Marvel) first appears in Amazing Spider-Man V1 #41.
Toro Rojo (Marvel) loses his horns in Thor V1 #290.