Continuing with the "eye" theme, here's the Eye of the Beholder.
Following Krishnath's suggestion, this one will have 11 HD. Its game statistics are as follows:
Str 10, Dex 10, Con 10, Int 13, Wis 13, Cha 10
AC -4
100 HP
Special Abilities: fire, cold, acid, electricity, and magic resistance 20
Eye rays: Cause serious wounds, flesh to stone, anti-magic ray, domination, slow, death ray, charm person, fear
Beholderkin, Eye of the Beholder
Large Aberration
Hit Dice: 11d8+44 (93 hp)
Initiative: +7
Speed: 5 ft. (1 square), fly 20 ft. (good)
Armor Class: 24 (-1 size, +3 Dex, +12 natural), touch 12, flat-footed 21
Base Attack/Grapple: +8/+10
Attack: Eye rays +10 ranged touch
Full Attack: Eye rays +10 ranged touch
Space/Reach: 10 ft./5 ft.
Special Attacks: Eye rays
Special Qualities: All-around vision, antimagic cone, darkvision 60 ft., flight, resistance to acid 10, cold 10, electricity 10, and fire 10, spell resistance 23, telepathy 100 ft.
Saves: Fort +9, Ref +6, Will +11
Abilities: Str 7, Dex 17, Con 18, Int 17, Wis 15, Cha 15
Skills: Hide +13, Knowledge (arcana) +17, Listen +18, Search +21, Spot +22, Survival +2 (+4 following tracks)
Feats: Alertness (B), Flyby Attack, Great Fortitude, Improved Initiative, Iron Will
Environment: Cold hills and underground
Organization: Solitary, pair, or cluster (3-6)
Challenge Rating: 13
Treasure: Double standard
Alignment: Usually lawful evil
Advancement: 12-16 HD (Large); 17-33 HD (Huge)
Level Adjustment: --
An 8-foot diameter writhing mass of eyestalks, muscles, and nerves hovers in the air. A large eye and an exposed brain are nestled within the center of this mass.
Eyes of the beholder are mutant beholderkin created by Lycanth the Enlightented, a powerful wizard in the service of the dragon Abazigal. Because they are created via experimentation on standard beholderkin, true beholders and their kin will attack them on sight.
The first eye of the beholder was created by removing the chitinous exoskeleton from a standard beholder, and over time magical experimentation has created the monstrosity seen today. Its mouth has evolved into a simple feeding tube, only strong enough to pierce the outer layers of an eyeball. Its exposed nerves and muscles have toughened over time, although are not as tough as the exoskeleton of its original form.
An eye of the beholder gains nourishment by draining the viscious fluids from the eyes of the recently deceased with a long, thin feeding tube.
Eyes of the beholder understand the language of Beholders and Common, but only speak telepathically.
Combat
Like other beholders, an eye of the beholder often attacks without provocation, attempting to use as many of its rays as it can.
Eye Rays (Su): Each of an eye of the beholder's 10 eye rays resembles a spell cast by a 13th-level caster. Each eye ray has a range of 130 feet and a save DC of 17. The save DCs are Charisma-based. The 10 eye rays inclue:
Anti-magic: The target must succeed on a Will save or be affected as though within an antimagic field for 13 rounds. An eye of the beholder uses this ray to neutralize an enemy spellcaster or a particularly threatening magic item.
Charm Monster: The target must succeed on a Will save or be affected as though by the spell. An eye of the beholder uses this ray to confuse the opposition, usually employing it early in a fight. The beholder generally instructs a charmed target to either restrain a comrade or stand aside.
Dominate Monster: The target must succeed on a Will save or be affected as though by the spell. An eye of the beholder uses this ray to enslave thralls to do manual labor for it.
Fear: This works like the spell, except that it targets one creature. The target must succeed on a Will save or be affected as though by the spell. An An eye of the beholder likes to use this ray against warriors and other powerful creatures early in a fight to break up the opposition.
Finger of Death: The target must succeed on a Fortitude save or be slain as though by the spell. The target takes 3d6+13 points of damage if its saving throw succeeds. An An eye of the beholder uses this ray to eliminate dangerous foes quickly.
Flesh to Stone: The target must succeed on a Fortitude save or be affected as though by the spell. An eye of the beholder likes to aim this ray at enemy spellcasters. It also uses it on any creature whose appearance it finds interesting. (After the fight, the eye of the beholder has its thralls carry the statue to its lair as a decoration.)
Inflict Serious Wounds: This works like the spell, causing 3d8+13 points of damage (Will half).
Lightning Ray: This works like the lightning bolt spell, except that it is a ray instead of a line, causing 10d6 points of electricity damage (Reflex half).
Scorching Ray: This works like the spell, firing three simultaneous rays causing 4d6 points of fire damage each.
Slow: This works like the spell, except that it affects one creature. The target can make a Will save to negate the effect. An eye of the beholder often uses this ray against the same creature targeted by its flesh to stone or finger of death ray. If one of the former rays fails to eliminate the foe, this ray might at least hamper it.
Antimagic Cone (Su): An eye of the beholder's central eye continually produces a 150-foot cone of antimagic. This functions just like antimagic field (caster level 13th). All magical and supernatural powers and effects within the cone are suppressed--even the eye of the beholder's own eye rays. Once each round, during its turn, the eye of the beholder decides whether the antimagic cone is active or not (the eye of the beholder deactivates the cone by shutting its central eye).
All-Around Vision (Ex): Eyes of the beholder are exceptionally alert and circumspect. Their many eyes give them a +4 racial bonus on Spot and Search checks, and they can't be flanked.
Flight (Ex): An eye of the beholder's body is naturally buoyant. This buoyancy allows it to fly at a speed of 20 feet. This buoyancy also grants it a permanent feather fall effect (as the spell) with personal range.
The eye of the beholder first appeared in the Black Isle computer game Baldurs Gate II: Throne of Bhaal, (2001).