The last in a series can be described as the ultimate. A cheeky kid, when asked what she wants to be when she grows up, might say, "I want to be an actress, a singer, and a veterinarian, but my ultimate goal is to be President of the United States."
A definition for the adjective ultimate is the furthest in space or time or the highest in degree or order. Traveling for business, you are flying first to London, then to Portugal, but your ultimate destination is South Africa. The kids ask you if they can invite friends over to play video games. It's a good idea to reply, "Mom isn't home from work yet and she's ultimate authority on the schedule."