Yes! Prince Rhaegar Targaryen kidnapped Robert's betrothed, Lyanna Stark. Her father and eldest brother went to King's Landing to protest but Rhaegar's father, the Mad King Aerys killed them and gave the order to Jon Arryn to kill Robert Baratheon and Eddard Stark, his wards. Lord Arryn refused and Robert's Rebellion begun. Robert slew Rhaegar at the Battle of the Trident and the Kingslayer, Jaime Lannister, killed the Mad King during Tywin Lannister's sack of King's Landing.

[and thus ends your impromptu Westerosi History Lesson]

Not anyone. King Robert has a son, Prince Joffrey, who is a couple of years younger than I am, he'll be king when Robert dies.