Iron Golem

Often the enemy with the highest defense in any given Castlevania game.

Castlevania: Circle of the Moon
The Iron Golem is the third boss in Circle of the Moon, and guards the Kick Boots. It advances slowly, occasionally pausing to pound the ground, which releases gears from the ceiling. The Iron Golem also heals itself, and fires a spark that causes massive damage. It is one of the easiest bosses in the game.

Castlevania: Aria of Sorrow
The Iron Golem has 9999 HP and all attacks will only do 1 HP of damage. Using the Killer Mantle Soul will swap its 9999 HP with its 1 MP while simultaneously delivering 1 HP of damage, thus killing it in one hit.

Castlevania: Dawn of Sorrow
Almost all attacks are reduced to 1 HP damage, but as it has only 50 HP, it is substantially easier to kill than its Aria of Sorrow counterpart. It's attacks is a punch,a kick and that it will breath fire.To defeat it easy,use Puppet Master or Bat Company to come to it's backside as it cant turn around.

Castlevania: Portrait of Ruin
It has high defense, but still takes decent damage. Electric-based attacks (such as Chain Lightning) can kill it fairly quickly.