Who is Jon Snow's father?

In the beginning of the novel, Jon Snow’s father was said to be Eddard “Ned” Stark, but his mother was unknown. Even though Ned Stark was married to Catelyn “Cat” Stark, Lady Stark did not consider Jon Snow as her son. However, it is worthy to note that the 7th season of Game of Thrones finally revealed one important fact: That Jon Snow was the son of Lyanna Stark and Rhaegar Targaryen.

His original name was Aegon Targaryen, but Lyanna made Ned promise to keep Aegon safe from King Robert’s wrath thus, giving him the name Jon Snow. Now that the truth has been revealed, fans finally know that Jon Snow is Daenerys Targaryen’s nephew and the legitimate heir to the iron throne.