Tempest Shadow: Former general of the Storm King's army, former formibable foe and an expert in non-magical combat. After helping spread the word of the Storm King's defeat and helping the kingdoms he hurt recover, she spent a few years being Twilight's personal guard before the two started developing feelings. Now she's Twilight's wife and consort, living with her in the castle and raising their son together. The diadem she wears was developed by Twilight and Sunburst, and helps her use rudimentary magic even with the loss of her horn.
Prince* Dawn Bubble Berry Sparkle: Son of Tempest and Twilight, only child. Despite being the son of two magically powerful mares, BB has a very average level of magical skills. Like most unicorns, his magic is at its best when being applied to his special talent, which is Light Puppetry and the use of auras as a tool to tell stories. While he is nervous about one day having to taqke the throne in place of his mothers, he really does try his hardest to be a good leader despite his uncertainty around unfamiliar people.
Princess* Twilight Sparkle: Element of Magic, beloved Princess of Friendship and founder of the Equestria School of Friendship. As Princess of Friendship, much of her work as a leader involves engaging with representatives and visitors from Equestria's bordering countries and kingdoms, in addition to sometimes helping the Equestrian locals. Her School of Friendship has evolved from just focusing on friendship studies to also involving the study of various types of magic, including that of Earth ponies and Pegasi, whose own magics have been criminally under-researched.The school has attracted creatures from all walks of life, and most students who attend are somewhere in their teens (13-20).
*Twilight is technically more of a duchess, power-wise, since she answers to the Princesses in Canterlot and rules over a smaller area than them. The term "princess/prince" is often used in Equestria as a simpler way to refer to ponies that hold a lot of power and/or are close to the Royal Family. Prince Blueblood is technically only a Duke, but due to his proximity to Celestia he's called a prince.