Mechazaurus

Mechazaurus (メカザウルス) is a giant Brachiosaurus-like robot who is the boss of the first part of Wily's castle in Mega Man 6.

It attacks by spitting fireballs and shoots platforms from its chest. The weak spot is its eyes, but they can be hard to hit at times. If Mega Man is equipped with the Rush Power Adapter, he can charge up his punch to hit the platforms back at the Mechazaurus, dealing 1 point of damage each time.

Trivia
Mechazaurus' name and design is a homage to the monsters of the week of the same name in the 1974 anime Getter Robo.