Forms of Spike

Spike, in the course of his many (mis)adventures, took on a number of different alternate forms.

Adult

While suffering from greed-induced bigness, Spike went through several stages of increasing size as a result of accelerating maturation. In the first, he stood about the same height or slightly taller than Twilight Sparkle, with his limbs, body, and tail lengthening. These changes in dimension continued to increase, with his spikes growing longer and his muzzle more pronounced with each stage. By the time he reached maximum size, Spike towered over most Ponyville houses and could grip a full-grown mare, Rarity, in the end of his tail. His head spikes had also become long and sharp in appearance, with his teeth growing longer and sharper with an additional pair jutting out from under his top lip.

Spike later achieved his adult form yet again through the use of a magical potion created by Princess Amore. He retained his usual personality, however, rather than becoming consumed by greed, and was thus able to use his increased stature to the advantage of himself and his friends.