Dreadnought

Dreadnought is an creature type that is only used once, for the artifact creature card Phyrexian Dreadnought from Mirage, designed by Mark Rosewater.

A dreadnought originally is a type of battleship armed with heavy-caliber guns in turrets. The term is also used to describe something that is among the largest or most powerful of its kind, which definitely suits a Phyrexian 12/12 artifact creature with trample.

Trivia

 * Originally subtype-less, the subtype Dreadnought was especially created for this card in the Grand Creature Type Update. It later gained the Phyrexian subtype after Modern Horizons 2, and now is on the shortlist as a creature whose name equals its creature types]].
 * Mark Rosewater believes that the people who designed Consulate Dreadnought did it in reference of Phyrexian Dreadnought.