Back in the day, White Dwarf magazine was the British answer to the Dragon, and its regular "Fiend Factory" column was a source of many monsters for early D&D games. In fact, the first edition Fiend Folio (1981) was largely a collection of monsters submitted to WD. This 3e conversion is part of an ongoing project to resurrect some interesting WD monsters that, for one reason or another, fell by the wayside. The uncredited spikehead appeared in "Fiend Factory: Near Misses" from White Dwarf 27 (Oct/Nov 1981). This Fiend Factory was the third of three articles detailing monsters that, for one reason or another, were cut from the original Fiend Folio.
You see a squat, ape-like beast with powerfully built and abnormally long arms. A wicked bone horn projects two feet from the center of its forehead.

Spikehead illustration by Russ Nicholson copyright © 1981. Used without permission.
Usually N Large magical beast
Init +1; Senses darkvision 60 ft., low-light vision, scent; Listen +3, Spot +3
AC 16, touch 10, flat-footed 15
(-1 size, +1 Dex, +6 natural)
hp 30 (4 HD)
Fort +6, Ref +5, Will +4
Spd 20 ft. (4 squares)
Melee gore +10 (2d6+9)
Space 10 ft; Reach 10 ft
Base Atk +4; Grp +14
Special Atk constrict 1d8+9
Abilities Str 22, Dex 13, Con 14, Int 3, Wis 12, Cha 8
Feats Iron Will, Weapon Focus (gore)
Skills Climb +8, Jump +1, Listen +3, Spot +3
Environment any hills or mountain
Organization solitary, pair, or troop (3-20)
Treasure standard
Advancement 5-8 HD (Large), 9-12 HD (Huge)
Constrict (Ex) A spikehead deals 1d8+9 points of damage with a successful grapple check.
These uncommon creatures do not speak and communicate with each other by grunts.
Spikeheads are ferocious fighters and will attack a party of any size. A spikehead will charge on a chosen victim and attempt to grapplea successful hit indicates that it may constrict.