Dire Rhinoceros (CR 9)

Huge Animal
Alignment: Always neutral
Initiative: +5; Senses: low-light vision, scent, Listen +13, and Spot +13

AC: 21 (-2 size, +1 Dex, +12 natural), touch 9, flat-footed 20
Hit Dice: 17d8+153 (229 hp)
Fort +19, Ref +13, Will +6
Speed: 30 ft.
Space: 15 ft./10 ft.
Base Attack +12; Grapple +30
Attack: Gore +21 melee
Full Attack: Gore +21 melee
Damage: Gore 2d8+15/17-20/x3
Special Attacks/Actions: Augmented critical, trample
Abilities: Str 30, Dex 13, Con 29, Int 2, Wis 13, Cha 10
Special Qualities:
Feats: Alertness; Improved Bull Rush; Improved Critical (gore); Improved Initiative; Lightning Reflexes; Weapon Focus (gore)
Skills: Hide -7, Listen +13, and Spot +13
Advancement: 18-34 HD (Huge); 35-51 HD (Gargantuan)
Climate/Terrain: Temperate and cold plains or tundra
Organization: Solitary or herd (2-12)
Treasure/Possessions: -

Source: Fiend Folio

Augmented Critical (Ex): A dire rhinoceros's gore attack threatens a critical hit on a natural attack roll of 17-20 because of the creature's augmented critical ability and its Improved Critical feat. On a successful critical hit with a gore attack, a dire rhinoceros deals triple damage.

Trample (Ex): As a standard action, a dire rhinoceros can trample opponents at least one size category smaller than itself. This attack deals 2d12+15 points of bludgeoning damage. A trampled opponent can attempt either an attack of opportunity at a -4 penalty or a Reflex save (DC 28) for half damage.

Scent (Ex): A dire rhinoceros can detect approaching enemies, sniff out hidden foes, and track by sense of smell.

A dire rhinoceros always initiates combat with a charge attack if it can, so that it can wade into the midst of its enemy with its horn.

Dire rhinoceroses can be summoned using a summon nature's ally VII spell.