The only thing scarier than a dragon, a three-headed dragon? The creature may be best remembered as a foe of Godzilla, but the titular star of Ghidorah... (and its signature shrieks) has become so iconic, it's almost as recognizable as the series' mutated hero.
The reasons for that are fairly obvious: gifted with a trio of heads, arms are rendered a complete afterthought. Differing from other Godzilla monsters in that it hails from outer space, and breathing 'Gravity Beams' as opposed to fire, Ghidorah remains the most invincible 'dragon-like' creature on record.
The only possible challenger: Mecha-King Ghidorah.