Rumor has it the Leopard originated as a secret project in the Minmatar Republic. In their endless battle against enslavement by the Amarr Empire, the Minmatar have had to develop ways not only to liberate large masses of their people, but also to sneak in and capture individuals of high strategic importance.
These kinds of black ops search-and-rescue missions might be executed for key people who were held by the enemy and possessed either special qualities the resistance needed, or information the Republic couldn't afford having tortured out of them. It's notable that these individuals might not all have been Minmatar, and that the resistance movement is unlikely to have restrained itself from using the same methods on key Amarr people they'd captured with the help of the Leopard.
It is an extremely fast ship, meant for quick and stealthy getaways, and while its origins are covered in rumors, chances are the Minmatar leaked it to the capsuleers in order to curry favor with them.
The Leopard is a special release ship that was gifted as the final item in the 2013 holiday “Yule Lads” giveaway, one ship to each active account that requested it. The Leopard is the fastest ship (at warp speed) in the game.