Renly Baratheon

"The Targaryens called Robert usurper. He seemed to be able to bear the shame. So shall I."

- Renly to Stannis, trying to justify his actions. Renly Baratheon is the Lord of Storm's End, Master of Laws on Robert's Small Council and the younger brother of King Robert I Baratheon and Stannis Baratheon. His parents were Lord Steffon Baratheon and Lady Cassana Estermont. During the Siege of Storm's End by the Tyrells and Redwynes, Stannis cared for Renly, holding the castle for a year. Despite this, Robert made Renly Lord of Storm's End and Stannis Lord of Dragonstone, a less pleasant and more poorer keep. During his youth at Storm's End, Renly took Loras Tyrell as his squire and later they became lovers.

Not long before the War of the Five Kings,  Renly and Loras tried to have Robert marry Lady Margaery Tyrell as his new queen.

After Robert is fatally wounded by a boar, Renly schemes to usurp the Iron Throne from Joffrey, not realizing Cersei's children are illegitimate. He already has large numbers of troops due to ruling the Stormlands and he marrys Margaery of House Tyrell, meaning the Tyrells, who rule the Reach the most populated region in Westeros, support him. With the largest army in the Seven Kingdoms, Renly declares himself King and is crowned in Highgarden, the capital of the Reach. The noble houses of the Stormlands declares for him and ignores King Stannis' letters and claim to the Iron Throne, including Stannis and Renly's maternal grandfather Lord Eldon Estermont.

Renly moves his large army towards King's Landing, blocking off the Rose Road which brings starvation to King's Landing. However he receives word that his older brother Stannis, who has also declared himself King on the grounds that Robert has no legitimate children, is besieging Storm's End. Renly travels there and parleys with Stannis. He sneers at Stannis' claims of the illegitimacy of the Queen's children, thinking Stannis is the same as him but with less charisma and claiming nobody wants Stannis for their King. Stannis offers that if Renly bends the knee to him he'll let him remain Lord of Storm's End, keep his seat on the Small Council, and make him his heir until he has a son. Renly refuses this. He plans to destroy Stannis' army the next day and talks of how his forces will kill Stannis. However, a shadow assassin the Red Priestess Melisandre has conceived with Stannis stabs Renly dead. Stannis is upset at Renly's death, but believes it was necessary. On his death, most of the houses of the Stormlands and a few of the Reach who were loyal to him declares for Stannis, the first one being Lord Alester Florent, Queen Selyse's uncle. However the Tyrells with Lord Randyll Tarly and Lord Mathis Rowan flee back to the Reach, and later Lord Mace Tyrell, wanting Margaery to be Queen, decides to support the Lannisters.

During the Battle of the Blackwater, Renly's ghost apparently fights alongside the Tyrells, helping to defeat Stannis' army. However, in reality Garlan Tyrell wore Renly's armor. Despite the fact Renly was planning to overthrow Joffrey, he is remembered in song as a heroic figure for helping to defeat Stannis.

Trivia

 * Due to his more affable and heroic nature in the television adaption, many don't realize how villainous Renly's actions are. His brother Stannis does indeed have a legal claim to the throne, but because Renly thinks he would be a better ruler, he is literally willing to go to war with his brother (in an already war torn and divded nation) and ultimately murder him for an unfounded claim.
 * Renly's sexuality is left more ambiguous in the books (due to him not being a POV character), but Georfe R.R. Martin confirmed he and Loras Tyrell were lovers.
 * Renly is the first king who dies during the War of the Five Kings.