Aeons, eidolons, guardian forces, espers... These primal forces go by many names in the Final Fantasy universe. In many instances, they can be called upon to use their trememdous powers to aid the adventurers of Final Fantasy. Other times, they serve as monstrous bosses that must be overcome.
The mighty Titan usually takes the form of a powerful giant with the ability to rend the very earth asunder. This behemoth usually makes use of one of several dedicated attacks, including Gaia's Wrath, Anger of the Land, or Earth Fury, and deals earth elemental damage. Titan is one of the longest-running summons in the franchise, with his appearances only falling behind the likes of Ifrit, Shiva, and Bahamut.
Final Fantasy 3
In Final Fantasy 3, Titan can be summoned by evokers, summoners, and sages. It is obtained by purchasing the level five summon magic spell, Hyper.
Final Fantasy 4
Much like Shiva, Titan joins the party once Rydia does in Final Fantasy 4. She initially summons Titan in battle against Cecil and Kain in Mist when she finds out they had killed the Mist Dragon. During the battle, Titan shakes the earth and the ensuing landslide separates the Mist Valley from the Damcyan Desert. Titan would go on to reprise his role as a boss in both Final Fantasy 4 -Interlude- and Final Fantasy 4: The After Years.
Final Fantasy 5
Titan acts as a boss that the party must overcome in Final Fantasy 5. After besting the behemoth, it becomes a level three summon for the summoner job class.
Final Fantasy 7
In Final Fantasy 7, the Titan summon materia can be located in the destroyed Gongaga mako reactor. It isn't immediately visible to players, but can be found by interacting and observing the ruins of the reactor. Once summoned, Titan will cast Anger of the Land.
Final Fantasy 9
Titan can be called upon by the summoner Eiko, in conjunction with the eidolon Fenri,r in Final Fantasy 9. He uses the skill Terrestrial Rage and sports a unique, horned appearance.
Final Fantasy 11
The Titan of Final Fantasy 11 is actually a former member of a race of titans that lived in the south of the Quon continent. This race was seemingly wiped out by the people of a neighboring city over a dispute involving a bordering forest. A sole titan survived the attack and was found by a young girl named Daemdalus, who nursed him back to health.
This didn't sit well with the local population who captured the Titan and planned to execute him. Before they could carry out their nefarious plan, Daemdalus threw herself in front of Titan. The goddess Altana took pity on the pair and called them to the heavens. Titan became the Avatar of Earth and Daemdalus became the brightest yellow star in the Titan constellation.
Final Fantasy 13 Series
The Titan of Final Fantasy 13 is a fal'Cie charged with watching over Gran Pulse. Titan presides over a series of missions known as "Titan's Trials." Its primary objective is to guide the evolution of the Gran Pulse fauna. However, it is later discovered during Lightning Returns as a ruin, with its remains scattered across the Dead Dunes.
Final Fantasy 14
The primal Titan is woshipped by the kobold tribes of Eorzea in Final Fantasy 14. Though a benevolent god to his worshippers, Titan is a literal force of nature to those that would provoke him. He first appeared in patch 2.0 with Ifrit and Garuda.
Final Fantasy 15
Titan is one of six Astrals that stand watch over the world of Eos in Final Fantasy 15. He is awoken by the Oracle Lunafreya and psychically beckons Prince Noctis to him. Once the intense trial-by-combat is completed, Titan can be summoned in certain circumstances.