Question: who is aegon targaryen to jon snow?
Answer: Prince Aegon, the first son of Prince Rhaegar Targaryen. He was murdered along with his mother, sister, and grandfather during the Sack of King's Landing. Jon Snow, the second son of Prince Rhaegar by Lyanna Stark, also named Aegon Targaryen. In the event that he should ascend the throne, he would rule as "Aegon VI".