House Baratheon of Storms End is one of Great Houses of Westeros, and principal house of the Stormlands. The Baratheons and their bannermen were instrumental in the rebellion against Targaryens.
Their sigil is a crowned black stag on a field of gold, and their words are "Ours is the Fury".
Robert Baratheon, the head of House Baratheon, was crowned King of the Seven Kingdoms after his successful rebellion against the mad King Aerys.
Robert had been betrothed to Lyanns Stark (sister of Eddard), but after her death, Robert married Cersei Lannister to maintain political stability.
Joffrey Baratheon is the eldest son and heir of King Robert Baratheon and Queen Cersei Lannister.
Speculation regarding his real parentage is a key element of the story, given that all Robert's illegitimate children have his dark hair.
Stannis Baratheon is Robert Baratheon's next oldest brother.
After Robert's death, Stannis disputes the legitimacy of Joffrey's claim to the Iron Throne.
Cersei Lannister is the eldest child of Tywin and Joanna Lannister and the twin sister of Jaime Lannister.
After Robert's Rebellion she married Robert Baratheon, and became Queen of the Seven Kingdoms, but she is a Lannister through-and-through.
She is the mother of Joffrey, Myrcella, and Tommen Baratheon.
Melisandre is a priestess of the faith of R'hllor, a follower of the Lord of Light.
She is from the eastern city of Asshai, but has joined forces with Stannis Baratheon, and has become an influential advisor to him.