What is the rarest Star Wars toy ever made?

Could you please elaborate on what makes a Star Wars toy considered to be the rarest of all? Is it the limited production numbers, the exclusivity of the toy, or perhaps its unique history and association with the franchise? Are there any specific Star Wars toys that are known to collectors as being exceptionally rare, and if so, what sets them apart from the rest? Furthermore, what factors contribute to the value and desirability of these rare Star Wars toys in today's market?