Kaijura (CL OMG / campaign-ending XP)
Hugemongous. Radioactive. Stomps cities. You get the picture. Just don't apply the "solo" template or we're all screwed.
Colossal Beast (aberration, unique) 40
Sanity Loss 1d10/2d10
Init +22; Senses Perception +27, Darkvision, Low-light Vision
DR 25, radiation/electricity 50; Immune mind-influencing effects; Resistance spells +20
Defenses Ref 53 (flat-footed 51), Fort 38, Will 24
hp 959; Threshold 93
Speed 12 squares, swim 30 squares
Melee slam +49 (4d6+39) and tail slap +47 (3d6+37) plus stomp
Ranged breath ray +38 (13d6+20) area effect: line 2 squares x 2 squares x 60 squares
Fighting Space 6 squares x 6 squares; Reach 4 squares
Base Atk +30; Grp +67
Abilities Str 45/+17, Dex 14/+2, Con 47/+18, Int 6/-2, Wis 15/+2, Cha 30/+10
Feats Extra Second Wind, Improved Damage Threshold, Indomitable, Mighty Swing, Power Attack, Shake It Off, Skill Training (Climb), Skill Training (Endurance), Skill Training (Jump), Surefooted, Toughness, Trip, Weapon Focus (slam), Weapon Specialization (slam), Weapon Familiarity (Natural Weapons)
Skills Climb +42, Endurance +43, Jump +42, Perception +27, Swim +42
Damage Reduction Kaijura gains DR 50 against radiation or electricity.
Frightful Presence As a free action, Kaijura gets an attack at +30 vs. the Will defense of any creature of large size or smaller within 20 squares. A successful attack indicates that the target has -2 to all ability checks, skill checks, attacks, and defenses against Kaijura for 10 rounds.
Natural Armor Kaijura's thick, scaly hide gives it +30 natural armor and provides DR 25.
Natural Swimmer Kaijura gets training in the Swim skill for free. It may take 10 on any Swim check, even if rushed or distracted.
Spell Resistance Kaijura gets +20 to all its defense scores against spells.
Stomp By moving through the space of any creature or object of size huge or smaller, Kaijura gets an attack at +37 vs. the Ref defense of that creature as a free action. A successful attack does 3d6+20 damage to the target as Kaijura stomps on them.
Unique As a unique creature, Kaijura adds ½ its level to its defense scores and gets 3x its maximum hit die at 1st level as if it were a heroic character.
They don't get much scarier short of rising up from R'lyeh.