Terra

Terra is one of the main protagonists in Kingdom Hearts Birth by Sleep. From the view of the story, it is revealed he is a Keyblade Wielder before Sora. Terra, along with Aqua and Ventus, fights against Master Xehanort and Vanitas. He is the oldest of the three Keyblade Warriors when it comes to age. Like Aqua, it is his dream to become a Keyblade Master.

While Terra means "Earth" in Latin, Riku's name in Japanese means "Land", although their only connection is that Terra chose Riku to wield the Keyblade sometime in the future.

Kingdom Hearts Birth by Sleep
Terra was sent by Master Eraqus to seek out Master Xehanort and his cohort Vanitas who had previously disappeared. Though he took the Master Qualification Exam alongside Aqua, Terra was unable to become a Keyblade Master due to being unable to control his darkness. Unbeknownst to them, Master Xehanort was responsible for the appearance of such darkness during the exam.

Terra locates Master Xehanort in the Radiant Garden, seemingly having been captured by Braig. When Terra battles Braig, he nearly loses until he uses his darkness to gain an advantage. Braig loses his right eye and is scarred when Terra temporarily loses some control over his newfound powers.

He is believed to have succumbed to darkness for power because of Master Xehanort, believing he had done something to his heart. In the end of the game, Master Xehanort's heart possesses Terra's body and mind, transforming him into the young Xehanort while part of Terra's soul finds residence within his armor. With the use of his Keyblade, Terra's armor engages the new Xehanort in a fierce battle, and wins, but only succeeds in knocking Xehanort out long enough for him to be transported to the Radiant Garden.

Aqua sees Terra at Radiant Garden, not knowing he is the new Xehanort and approaches him. Terra/Xehanort then duels Aqua, using his Keyblade and summoning his Guardian to fight her as she defeated him on equal terms. The battle resumes until Terra temporarily regains control of his body. Master Xehanort then uses his Keyblade to try to lock his own heart to prevent further influence from Terra's heart. This results in Xehanort being consumed by darkness and sent to the dark realm. In an effort to save Terra's body, Aqua leaps into the dark realm and uses both her armor and keyblade to save Terra, leaving her stranded in the dark realm and Terra at Radiant Garden without a memory.

Terra's consciousness still resides within the new Xehanort along with that of Master Xehanort. He resolves to keep Xehanort at bay at all costs, even if the latter is sure his plan will develop nonetheless. At the game's climax, he is seen with Ventus in what appears to be the Land of Departure, and the two utter Sora's name with renewed hope.

Kingdom Hearts II
Terra does not make a physical appearance in the game, but is mentioned in The World That Never Was when Sora encounters Xigbar, who mentions "other Keyblade bearers", refering to Terra, Aqua and Ventus. The Lingering Sentiment serves as an optional boss in the Kingdom Hearts II Final Mix version of the game.

Abilities
Terra is the most powerful of the trio in terms of the damage aspect. He uses slow, but very heavy and hard-hitting attacks to decimate his enemies. On top of that, he has access to both a variety of magical spells as well as heavy physical strikes. His known Mode Changes are:

Level 1 Command Styles

 * Fatal Mode: An exclusive powerful fighting style for Terra that utilizes slow, but heavy hits to their maximum. Activated by filling the Command Gauge with physical-based commands.
 * Thunder Bolt: A swift Command Style that unleashes powerful lightning upon attacks. Activated by filling the Command Gauge with Thunder-based commands.
 * Fire Blazer: A ranged and versatile Style that focuses the Keyblade to erupt in flames while attacking. Activated by filling the Command Gauge with Fire-based commands.
 * Diamond Dust: An ice-based Style that seems to specialize in crowd-control and dealing with multiple enemies. Activated by filling the Command Gauge with Ice-based commands.
 * Ice Blast: Another ice-based style that uses an ice cream theme. Randomly activated by filling the Command Gauge with an Ice Cream item.

Level 2 Command Styles

 * Rock Breaker: After fulfilling certain requirements, his initial Style changes into Rock Breaker. A powerful and long-ranged Style that works best on the ground, it summons three large earth crystals from the ground to damage enemies. Activated by filling the Style Gauge with direct-hit-Keyblade physical commands.
 * Blade Charge: In this Style, the Keyblade resembles a purple sword. A long-ranged style, as its name implies, it allows the user to "charge up" the attacks for additional damage. Activated by filling the Style Gauge with Fire- and Ice-based commands.
 * Dark Impulse: A mode in which Terra summons the power of darkness to attack enemies. A versatile Style that hits enemies with slow, heavy attacks, but also exhibits long-range projectile attacks. Activated by filling the Style Gauge with Dark- and Gravity-based commands.

Additional abilities include:
 * Dimension Link: A mode that allows Terra to summon characters's powers from other worlds to aid him in battles.
 * Shoot Lock:
 * Star Burst: Multiple blasts of light fire from his Keyblade to hit the enemies. The input command is to continuously press [[File:B c.gif]]. “Fly shining blasts of light!” “Rapidly press the button to release the Finish command.”
 * Ultima Cannon: Terra transforms his Keyblade into a massive cannon and fires at enemies. It bears resemblance to a similar attack used by the Lingering Sentiment in Kingdom Hearts II Final Mix.
 * Sonic Shadow: Terra is surrounded by darkness and begins to dash through the enemies, just like Ventus' Photon Charge

Personality
He is the oldest and leader of the three Keyblade warriors. He has a calm and cool exterior, but he hides a heart that would fight for his friends. He and Ventus have a strong relationship because he said Ventus had saved his life before. Stubborn, strong-willed, and brave are his instant personality traits in most of the trailers we've seen so far. His personality is similar to Riku's.

Appearance
Terra is a tall young man with brown hair, blue eyes, and slightly tanned skin. Like his friends, Terra wears two intersecting straps over his chest, though his red ones are rather different, dropping much lower down and almost resembling criss-crossed suspenders. Also unlike Aqua and Ventus, Terra does not wear his badge (which is gold as opposed to the others' silver) on these straps. Instead, he wears it on his belt. He wears a skintight, black, high-collared shirt, showing that he is rather muscular. Terra's pants bear a distinct feudal Japanese style; his belt is tied like an obi-sash and he wears hakama (traditional samurai pants distinguished by the large pleats). His hakama are dark grey near the top, with several loops for his belt and two buttons, both of which are undone. The rest of the pants are tan with a small, lighter stripe of tan on the bottom hem. Terra wears a plain black wristband on his right arm, while his left arm is significantly more armored.

Like Aqua and Ven, Terra wears armor on one arm, with his bearing similarities to both of his companions. Terra's armor shares the large, ornate crest (colored gold) with Ven and the long, segmented section (each segment alternating between dark grey and dark red) with Aqua, though Terra's is much longer, reaching all the way to the bottom of his hand. He also wears a black, fingerless glove on his hand and what appears to be a black gauntlet on his forearm, over the segmented armor, which also has small pieces of dark red armor on it. Finally, his armored boots are dark brown and gold.

By touching the armor piece on his arm, Terra will become full clad in armor. When in his suit, Terra is clad from head to toe in armor, mostly in shades of dark brown, gold, and red. Dull orange lines decorate the armor as well. Notable additions to his armor include upturned, sharp red hooks on the backs of his boots, a navy blue cape, and a dark-visored helmet. His helmet sports two tall, red prongs on either side. Recent scans have shown Terra in his armor as part of the Joint Struggle mode. His armor is now slimmer, the colors on the armor are much brighter, and the cape is omitted. The dark brown is now shown to be black, as is the visor of his helmet.

Trivia

 * The Japanese Kingdom Hearts Birth by Sleep website's startup screen refers to Terra as the "Vast Earth Protecting Bonds" (絆守る大地).
 * In many language's, Terra is the word for Planet Earth.
 * Terra's belt buckle slightly resembles the symbol of the Heartless, except yellow. The badges on Ven's and Aqua's chests and Master Eraqus's belt have the same form as Terra's buckle, except white. Turned upside down, it vaguely resembles the symbol of the Nobodies.
 * It is still unknown what has become of Terra now that Xehanort, his Heartless ("Ansem"), and his Nobody (Xemnas), were destroyed. Terra is seen with Ven in what appears to be the Land of Departure after the events of Kingdom Hearts II, and he utters Sora's name with a hopeful smile (as does Ven). This will likely be explained in a future installment.