Darkhammer

The Darkhammer (ハンマーナック, Hanmaanakku) is the Mini-Boss of the Snowpeak Ruins in Twilight Princess. When defeated, the creature drops the Ball and Chain (not in a treasure chest), an item usable by Link. Following that, Link may proceed to open a chest Yeta thought contained the Big Key, but really had Ordon Goat Cheese.

Perhaps this is in reference to A Link to the Past, in which Princess Zelda, imprisoned in a cell in the dungeon of Hyrule Castle, is guarded by a knight wielding a ball and chain. Upon defeating the knight, Link receives the Big Key.

The Darkhammer is possibly a type of Lizalfos.

Strategy
Darkhammer will continuously guard his body with his massive Ball and Chain. In order to defeat him, you must use one of three strategies. One is to Clawshot a target behind him, as soon as he motions to throw his weapon. He will pause to pull in his weapon, so slash his exposed tail to damage him. The second is a quicker, but much riskier way. A split second after his weapon lands, roll behind him. As before, slash his tail. Quickly roll behind him while he is spinning his ball and chain(dodging quickly of course) and slash his tail like before. He can be killed instantly by a Mortal Draw to the tail, although the timing required makes it tricky to perform.

Trivia

 * The Darkhammer resembles the Darknut miniboss within the Temple of Time, not only by its prefix 'Dark-', but also because of its heavy armor suit and large weapon of choice.