Which exiled lord who raised Aegon Targaryen was omitted from Game of Thrones?

Jon Connington was the exiled lord who helped raise Aegon Targaryen, known in the books as Young Griff. A close friend of Rhaegar Targaryen, Connington briefly served as Hand of the King to the increasingly unstable Aerys II.

After failing to stop Robert's Rebellion, Connington was stripped of his lands and titles and sent into exile. In Essos, he later became the guardian and mentor of the boy presented as Rhaegar's surviving son. The pair eventually return to Westeros with plans to seize the throne while the realm is divided by war.

Connington appears as a viewpoint character in A Dance with Dragons. The television series omitted both him and the Young Griff storyline, instead developing Daenerys, Jon Snow, and Varys along different paths. A common mix-up is assuming Varys raised Aegon; Varys helped conceal and promote the boy's identity, but Connington was his principal guardian.