Silas Benjamin -- Kings
A soldier in the Unification War, Silas Benjamin was crowned king by God himself when he resolved to rebuild Shiloah, the capital city of Gilboa. Modeled on the biblical King Saul and played to perfection by Ian McShane, Silas would rather negotiate with than attack his opponents in the interests of peace and prosperity.
Teresa Mendoza -- Queen of the South
As the alter ego for protagonist Teresa Mendoza, The Queen of the South appears when things are looking their worst, providing Teresa with the emotional support and advice to survive. She is cool, collected, and ruthless. She is Teresa's potential future as leader of the Vargas cartel.
Eleanor Henstridge -- The Royals
The only daughter of a fictional British royal family, she's gone from stoner party girl to a royal focusing on social causes who is in a committed relationship with her former bodyguard. Multiple deaths and the realization of a serious addiction will do that to a person, I guess.
Crowley -- Supernatural
Talk about working your way up the ladder. Crowley's admission to Hell is bought by a deal his human persona struck to increase his penis length. Centuries of punishing torture later, he makes the leap to demonhood and then excels at that to win the King of the Crossroads title. After that, it's a hop, skip, and a jump to King of Hell. Not that holding onto that title has been easy. Seems like every year or two he needs to fight off a challenger for that particular throne.
Margo Hanson -- The Magicians
Pretty sure this is the first ruler to win authority on the write-in ballots of talking animals. As High King of Fillory, Margo has been a force for social justice amongst the many invested (and often combative) parties. Trained in the use of magic through her time at Brakebills, her quick-thinking strategy skills are all her own by nature.
Regina Mills -- Once Upon A Time
Regina Mills may have been evil and may now be good but she maintained her queenliness throughout it all. From the primary antagonist and the caster of the First Dark Curse (who knew there would be so many?) which created Storybrooke to the popularly appointed Queen of the United Realms, this is a character who demonstrated some extreme skills for adapting to a rapidly changing environment.