Firestar

"We know the Thunderclan leader was born a kittypet, but it makes no difference to us when a kit gulps it's first breath. Firestar has given his Clanmates a precious little chance to forget his kittypet roots. He is the champion of all cats who are not Clanborn. No cat would argue that Cloudtail is not a worthy warrior, or that Daisy does not serve the Clan well in the nursery. But you can see how other Clans are suspicious of Firestar's willingness to welcome loners and kittypets into the warriors' den. What was Mosskit's mother thinking when she brought this too-brave, too-curious kit into the forest? Was Bluestar blinded by the color of his pelt, knowing he fulfilled the prophecy that fire would save her Clan? Starclan wanted him as much as Bluestar did. Poor, Firestar, he scarcely seems able to close his eyes without some farsighted dream filling his mind. But he has handled this burden well, lived up to all of Starclan's expectations. Maybe it took more than a Clanborn cat to discover Tigerstar's treachery, or to bring Windclan home after they were driven out by Shadowclan. Even Sandstorm came to forgive Firstar, his kittypet roots and she is a cat whose opinion is worth a moonfull of prey! We should wish Firestar nothing but peace, and a long life. Who knows how everyone of Firestars nine lives will end."

Warriors: The Ultimate Guide
"This brave, bighearted ThunderClan leader started life as a kittypet named Rusty, and lived with housefolk for his first six moons. He inherited his father Jake's fascination with what lay beyond the Twoleg nests, in the woods where wild cats were rumored to live. A chance encounter with a ThunderClan apprentice named Graypaw led to an introduction to Bluestar, who saw in the young kittypet's flame-colored pelt echoes of a recent prophecy: "Fire alone will save the Clan."

Renamed Firepaw, and then Fireheart, the young ginger cat trained hard to become one of ThunderClan's most trusted warriors, and later, Bluestar's deputy. But his path was darkened by a feud with Tigerclaw, the former deputy who was driven out of the Clan when Fireheart uncovered his plot to kill Bluestar.

Firepaw's closest friends in the moons following his arrival were Graypaw, Ravenpaw, and the young medicine cat Spottedleaf. After Spottedleaf's death during a ShadowClan raid, he grew close to a feisty, russet-furred she-cat named Sandstorm, and soon after Fireheart became leader and took on the name Firestar, she gave birth to his daughters, Leafkit and Squirrelkit.

Firestar led ThunderClan during the Great Journey from the forest to the lake and helped establish all four Clans in their new homes. His untiring faith in StarClan gave him the strength to fight against illnesses, drought, Twoleg disturbances, and border clashes. Except one life loss to illness, he gave each of his nine lives for the sake of his clanmates--most of all his final life, lost in the battle against the Dark Forest. A blaze of lightning marked the moment that Firestar joined his warrior ancestors--ancestors not by blood, but by heritage, honor, and tradition.

Books
Firestar is seen in Tallstar's Revenge, Crookedstar's Promise, Bluestar's Prophecy, Yellowfang's Secret, Firestar's Quest, Skyclan's Destiny, Into the Wild, Fire and Ice, Forest of Secrets, Rising Storm, A Dangerous Path, The Darkest Hour, Midnight, Moonrise, Dawn, Starlight, Twilight Sunset, The Sight, Dark River, Outcast, Eclipse, Long Shadows, Sunrise, The Fourth Apprentice, Fading Echoes, Night Whispers, Sign of the Moon, The Forgotten Warrior, The Last Hope, The Rise of Scourage,  Shattered Peace, A Clan in Need, The Heart of a Warrior, Warrior's Refuge, Warriors Return, The Rescue, Secrets of the Clans, Cats of the Clans, Code of the Clans, Battles of the Clans, and The Ultimate Guide.

Trivia

 * Firestar's love relationship with Spottedleaf was never shown that often when she was alive because Firestar was only a new apprentice at the time. There probably wouldn't have been more relationship if she lived because medicine cats can't have mates
 * Firestar has never had feelings for Cinderpelt.
 * Scourge and Firestar share the same father, Jake.
 * Firestar loses a life helping Ravenpaw and Barley
 * Firestar was not killed by the burning tree, but instead died of his wounds from the battle.
 * Firestar is noted to look exactly like his father, Jake
 * In The Ultimate Guide, he was described with a red pelt.
 * It is said that Fireheart did not disagree with Graystripe's love for Silverstream because it was against the code, but because he thought he was being replaced
 * It is said that Bluestar did not just like and trust Fireheart because of the prophecy, but because he reminded her of Oakheart. It is also said that is the reason Bluestar gave him the suffix 'heart' for a warrior name
 * Some believe that Spottedleaf was killed so Fireheart didn't have to choose between Fireheart and Sandstorm
 * Cinderpelt was always in love with Firestar, but Firestar never knew.

Funny Jokes:

 * 1) He likes to randomly go to his Clan's borders and run over them quickly and then return. He does this several times in a row.
 * 2) He once had a dream in which Tigerstar was nice, Sandstorm went on Americon Idol, Leafpool left to go to WindClan, Brambleclaw stole his den and wouldn't come out, and Squirrelflight ate all the fresh-kill
 * 3) He once woke up at two in the morning and ran around camp singing "We are Family". Surprisingly, nobody noticed.
 * 4) He likes to lead Longtail around in circles.

Taken from the book Warriors: Cats of the Clans by: Erin Hunter Taken from the book Warrios: The Ultimate Guide by Erin Hunter Some information came from the Warriors Wiki