#095 Onix
Onix's artwork for Pokémon FireRed and LeafGreen.
Category Rock Snake Pokémon
Original Region Kanto
National Dex Nr. #095
Kanto Dex Nr. #095
Johto #062
Hoenn #265
Sinnoh #034
Unova #071
Kalos #053 (Coastal)
Generation 1
Pokémon Color Gray
First Appearance Pokémon Red and Blue
Latest Appearance Pokémon Omega Ruby and Alpha Sapphire
Type(s) Rock/Ground
Ability/ies Rock Head, Sturdy
(Hidden: Weak Armor)
Average Height 28'10"
Average Weight 463.0 lbs.
Evolves Into Steelix

Onix (Japanese: イワーク Iwark) is a dual-type Rock/Ground Pokémon.

It evolves into Steelix when traded holding a Metal Coat.


Onix resembles a giant chain of gray boulders that become smaller towards the tail. There is a rocky spine on its head and a pair of black eyes right beneath it. This Pokémon has a magnet in its brain that serves as an internal compass. Its body absorbs many hard objects, making its body very solid. As it grows older, it becomes more rounded and smoother, eventually becoming similar to black diamonds.

Onix tunnels under the ground at over fifty miles per hour, which causes tremors and a terrifying roar that echoes a long way. The massive, winding tunnels it leaves behind are used as homes by Diglett. Onix loves to eat the large boulders it encounters while burrowing underground. As seen in the Pokémon Stadium series, Onix is capable of rotating its head, or any part of their body, a full 360 degrees. It is a very aggressive Pokémon that will constantly attack humans and Pokémon when it is in pain, as seen in the anime. Onix can be found in mountains and caves, though it prefers underground tunnels with little light.


  • Onix is the largest and heaviest Pokémon that evolves once.
  • Onix is the only unevolved Pokémon that is used in the Pokémon World Tournament by Trainers beyond the right attendant.
  • Of all the Pokémon that can evolve, Onix has the highest base Defense.
    • When holding an Eviolite, Onix can reach a maximum Defense stat of 690. This is the highest Defense stat obtainable without the assistance of stat modifiers, Abilities or items with adverse effects.
  • The Onix line is the only one which can be completely acquired with in-game trades. However, this is only possible in Pokémon HeartGold and SoulSilver, in which the player can trade Bellsprout for Onix in Violet City, any Pokémon for Steelix in Olivine City.
  • The Lagging Tail held item resembles the end of Onix's tail.
  • Onix is the tallest Rock-type Pokémon.


Onix is most likely based on a combination of a snake and earthworm. It may also been based on the wyrm, a type of dragon that has been presented as limbless and burrowing.

Name Origin

Onix is a corruption of onyx (a mineral).

Iwark may be a combination of 岩 iwa (rock) and スネーク snake.


Base Stats
Sp. Attack
Sp. Defense




National Pokédex
← #094: Gengar
#095: Onix
#096: Drowzee →
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