Unicron and a 10-cent coin.

With a height of 71 cm and a girth of 83 cm, Unicron is the biggest transforming Transformer ever to hit the homes of collectors — and he's got all the bells and whistles that you'd expect. He transforms into an evil planet (can you think of anything larger?) that eats other planets, and first appeared in Transformers: The Movie (1986), where he was the central antagonist that the original Transformers had to defeat.