Having been orphaned by a railway accident in 1885, Milo Thatch was raised and educated by his grandfather Thaddeus Thatch (see related files: Archeological Expeditions led by, Diplomatic Relations brokered through, Patents held by, and Georgetown Incident).
Milo took after his grandfather with regard to his affinity and passion for languages and antiquities. Graduated Buford Beaumont High School at age 11, accepted (and declined) admission at Harvard, Yale, and Princeton Universities for advanced academic studies, 1895. Enrolled at Oxford University, 1896. Tried out for Rowing Team, 1899 (rejected); Archery Team, 1900 (rejected); Debate Team, 1900 (accepted); Cricket Team, 1901 (rejected); and Chess Team, 1902 (accepted).
The development of Milo as a hero was a difficult one for the filmmakers. Heroes, in general, have been widely regarded as the least interesting for animators to work on, so the filmmakers sought to develop Milo as a character with a great deal of personality. There was an early concept that Milo was the descendant of Blackbeard the pirate, but that was abandoned in favor of Milo discovering his inner self and love for exploration rather than his inner pirate.
The supervising animator of Milo was John Pomeroy. Pomeroy had the unique challenge of trying to figure out what a linguist looked like and, according to Marc Okrand, who developed the Atlantean language for the film, used him as a basis for the design of the character. Pomeroy has also noted that Milo was the closest in his then thirty years in the business that he had animated a self-portrait. Because Milo appeared in virtually every scene of the film, he was one of the few characters requiring a team of animators working under Pomeroy.
Michael J. Fox provided the voice of Milo. Fox reportedly had to decide between this film and Titan A.E., another science fiction animated feature from Don Bluth and left it to his son to decide. Fox enjoyed not having to worry about the way he looked and could do what he needed, be it contorting himself, in order to project the right emotion through his voice. Co-director Gary Trousdale noted that Fox, despite being in his late thirties at the time, could still project a youthful exuberance needed to voice a character like Milo. James Arnold Taylor would replace Fox in the sequel for budgetary reasons.
In 1914, Milo James Thatch is working as a linguist at the Smithsonian Institute in Washington, D.C. He is preparing for a presentation he has scheduled with the board of directors to seek funding to locate a book called the Shepherd's Journal in Iceland, believing it will lead them to Atlantis. Shortly after four o'clock, he receives notice that the meeting had to be moved to three-thirty. He then immediately receives another notice that the matter is closed due to his supposed no-show.
Furious by the deceit, he chases after the board members and manages to catch his boss, Fenton Harcourt. Harcourt lays it thick that the museum only funds expeditions based on fact and not folklore, also belittling Milo's skills by saying that he is needed to tend to the boiler during winter. Milo attempts to hand over his letter of resignation, but Harcourt adds that no other institute would fund his expedition and he would throw his career away just like his grandfather. He tells Milo that he has potential, and he shouldn't throw everything away chasing a fairy tale.
A disheartened Milo returns home to find Helga Sinclair waiting to bring him to her employer, discovered to be a friend of Milo's grandfather in Preston Whitmore. Whitmore presents a parcel from Milo's grandfather that turns out to be the Shepherd's Journal. After a test by Whitmore on Milo's commitment to finding Atlantis, he reveals that the expedition is all set and ready to go. All that's left is for Milo to fill in for his grandfather to translate the directions from the book.
Milo has difficulty getting along with the others of the expedition, some even pulling pranks on him. In the end, they finally let him in during a rest stop. They manage to get him to stop reading the book for a moment, even though there appears to be a page missing. Milo and some of the others begin to open up about themselves. In the middle of the night, Milo awakens to use the restroom. He accidentally points his flashlight at a lamp housing fireflies that attack. The expedition is dropped into a cavern with Milo seemingly separated from everyone else.
When Milo comes to, he finds himself surrounded by strange figures. Upon noticing a scar on his shoulder, one of the figures removes its mask, revealing itself to be a human woman. Milo watches in shock as the woman uses a crystal to completely heal his scar. The figures make off with Milo following until he finds himself looking at Atlantis, alive and thriving. The figures return and he recognizes them as Atlanteans, able to communicate with them until it is discovered that they can speak other languages since they root back to Atlantean.
Though the meeting with the Atlantean King Kashekim Nedakh does not go so smoothly, the woman Milo met, revealed to be Princess Kidagakash Nedakh, leads him on a tour of the city while they get to know one another. Milo's interest in looking for the power source is sidetracked when he discovers that no one in the city can read the Atlantean language or even remember much of their past culture. Kida leads him on a swim where numerous writings are found and Milo begins to understand the true nature of the power source known as the Heart of Atlantis, as it is responsible for keeping the city alive.
Upon surfacing, Milo learns of Lyle Rourke's true intentions, having been the one who stole the missing page from the book and leading the rest of the expedition to find the crystal and sell it on the black market. Milo does not join them but is forced to cooperate when Rourke has a gun aimed at Kida. Milo translates the page that the crystal is hidden in the King's Chamber, but does not understand the riddle. Rourke figures it out and forces Milo, along with Helga forcing Kida, to descend into the Crystal Chamber to recover it. Milo and Rourke argue about how to bring the crystal down until Kida is called upon by the crystal and they bond.
As Rourke and the expedition prepare to leave with the Heart of Atlantis, Milo makes one last plea to them to reconsider their actions as it would kill the Atlanteans. Rourke punches him, but the majority of the key members of the expedition end up siding with Milo. Milo learns from the dying king that he must also save Kida, for if she remains bonded to the crystal for too long, she will be lost to it forever. After a pep talk from Joshua Sweet, Milo leads the others in using Ketaks to stop Rourke.
During the battle, Milo and Vinny Santorini act as decoys while Sweet and Audrey Ramirez attempt to free the container holding Kida and the Heart of Atlantis. When Rourke and Helga force them to retreat, Milo crashes his stone fish into the Gyro-Evac and causes it to descend, although Rourke gets it back going by tossing off everything else including Helga. As Rourke and Milo fight, Helga destroys the main balloon using a flare gun, causing Rourke to become enraged. Rourke attacks with an ax, smashing a glass cover. Milo notices energy from the crystal seeping into the glass shards and uses it to cut Rourke, turning him into a crystal. A chance swing by Milo causes Rourke to shatter against the moving propellers.
Though Milo and the container avoid the Gyro-Evac crashing upon them, it does result in the volcano awakening. Milo and the others manage to get the Heart of Atlantis back to the city in time to save it and Kida is freed from the crystal. Milo chooses to stay behind to help the Atlanteans rediscover their lost culture and has also fallen in love with Kida. He slips a package to be given to Whitmore on the surface, thanking him for his belief in the Thatches. Now, King of Atlantis, Milo constructs the stone effigy of Kida's father to join the other stone effigies of the past kings that orbit the Heart of Atlantis now hovering over the restored city.
Milo returns in the sequel. The film consists of three shorts that had been meant for a failed television series called Team Atlantis. James Arnold Taylor replaces Michael J. Fox as Milo's voice. The film's opening reveals that Milo has married Kida, who is ruling Atlantis as its Queen, with him as its King. The two are said to be working together to restore Atlantis to its former glory. When Milo's comrades make an unexpected arrival in Atlantis, Milo learns that a creature called the Kraken, an Atlantean defense mechanism, is reigning havoc in Newfoundland. Together with his comrades and Kida, Milo travels to Newfoundland to stop the creature. They learn that the Kraken has been attacking ships and taking the cargo to a village called Krakenstaff, said to be devoid of spirits and run by a corrupt magistrate named Edgar Vulgud, who made a deal with the Kraken to gain immortality but forgot to ask for eternal youth, but are able to defeat the Kraken by blowing it up, thus, killing Vulgud as well. Later, Milo and the group travel to the southwest to investigate a group of coyote spirits.
They find a hidden city which has Atlantean style statues. Milo and the group are forced to combat a businessman named Ashtin Carnaby, who intends to steal the statues and sell them. Coyote spirits interfere and turn Carnaby into one of them. Finally, Milo and the group are asked by Whitmore to find the Gungnir (Odin's spear, aka Spear of Destiny), a spear of Atlantean origin. It had been stolen by Whitmore's past competitor, Erik Hellstrom, who now believes himself to be Odin. Milo and the group track him to the Nordic mountains but are forced to rescue Kida, who is kidnapped by Hellstrom. Hellstrom reveals that he believes Kida to be his daughter, as well as his plan to end the world in Ragnarok. Milo and the others manage to rescue Kida and retrieve the spear after a difficult fight. At the end of the film, Milo is seen looking on as Kida chooses to combine the spear's power with the power of the crystal to raise Atlantis above the sea, as she had come to believe her father was wrong for hiding it. According to the ending narration, the world was made a better place as a result.
Milo Thatch appeared in "Goofy's Menu Magic".
Milo appeared at Disneyland and Walt Disney World during the time when the movie was first released. Milo and Kida appeared in a Ketak inspired car in Disney Stars and Motorcars before their float was replaced after a few years. The characters themselves disappeared from the parks several years after the film's release.
- According to the 2-disc DVD, before falling in love and marrying Kida, Milo's first love interest was named Lisa McGrath.
- Milo's complaint about how much he does not like carrots after puking over the ship used to launch the Ulysses could be a reference to how his voice actor Michael J. Fox is actually allergic to carrots, the line was ad-libbed by Fox, it wasn't supposed to be in the original script.
- Milo's decision to remain in Atlantis at the end of the film was actually better for him since due to the fact that the film was set in 1914, when World War I was already taking place, it would be inevitable for every single man in the United States to be drafted into the war, something Milo was apparently against. Also, it's implied that Milo never liked living on the surface until the Atlantis expedition.
- Milo's fighting during his final confrontation with Rourke was based on Jackie Chan's.
- Milo is the eleventh King of Atlantis.