Name: John of Austria, son of the Emperor Charles V.
Reason: I led the members of the Holy League in the Battle of Lepanto, in which we destroyed the Ottomans, and we can do it again. The Tercios are ready and they only need the order to attack.
I would prefer a plots system similar to CK2 instead of the assasins you described in the op. I find it too unrealistic (What is an silenced crossbow? How an assassin can enter in a castle, or exit?). And, if this feature were present in game, I agree with Lolbash: