There's something cool about a nobleman who grows up outside the confines of their lineage and learns to fend for themself and about the plight of common people, which then aids them when they finally return to reclaim their title.

King Arthur: Bat Themed Men. Arthur is the bastard son of Uther Pendragon, raised and taught by Merlin until he is ready to ascend the title of King of England. The OG boy King.

Aragorn (LOTR): Based on Arthurian Myth, Aragorn, son of Arathorn, is the last descendant of King Isildur of Gondor. Of the line of Numenor, Aragorn is blessed with a long lifespan, being 80 something during the main books. I kinda prefer the movie version where he's more hesitant to take the throne and has a more pronounced character arc.

Simba (Lion King): Probably everyone's go-to. Framed for his father's murder by his uncle, Simba is raised on an insectivorous diet by his adoptive dads and instructed in the deep philosophy of Hakuna Matata. 

Martin Septim (Oblivion): The bastard son of Emperor Uriel Septim the VII, Martin is hidden by the Emperor's bodyguards, The Blades, and raised on the outskirts of society, briefly joining the cult of Sanguine in his youth before joining the temple of Akatosh. His destiny finally came for him when his birth father and half brothers were assassinated, leading him to meet the Hero of Kvatch. Martin is a learned and kind man, who sadly did not get to be emperor long, sacrificing himself to defeat the demon god, Mehrunes Dagon.

Touchstone (Sabriel): Another bastard. Touchstone was more or less forced into being the heir when his half brother murdered the rest of their family and became an undead monster. Touchstone, driven mad by grief and rage, had to be turned to wood for the intervening years until his mind was healed. When he returned, he met with Sabriel and helped destroy his brother once and for all, before finally ascending the throne.

[Classic Trope] The Banished Prince/Heir