- For the new 2011 version, see Lion-O (2011 TV series).
Lion-O (voiced by Larry Kenney) is the son of Claudus, and is the leader and hereditary "Lord of the ThunderCats". His adventures are shown from childhood to adulthood on Third Earth and New Thundera, together with his friends and followers, the ThunderCats.
At the beginning of the series, Lion-O is a boy of mere twelve years old. He was among the group of Thunderian nobles to make the trip to Third Earth in the flag ship of the Thundercats, when their planet Thundera was destroyed. During this journey he aged physically until he became an adult of age twenty-four; this was due to the suspension capsule diminishing but not altogether preventing aging ("Exodus"). Coincidentally, such a malfunction did not occur with Wilykat and Wilykit, who were around the same age as himself, though as Lion-O recalls in the series' first episode, his mentor Jaga had mentioned that some aging does take place while in the Suspension Capsules in which he and the other Thundercats were placed when their flagship was damaged.
The now grown-up Lion-O assumed that this was the reason for his aging to adulthood, though he did not express any confusion regarding why WilyKat and WilyKit had not also aged as he had, which seems to indicate that he simply accepted it as a quirk of the capsules. Although cunning and skillful, he is truly a child in a man's body, and throughout the series, must learn what it takes to become a true leader and gain true maturity.
Lion-O is a Thunderian male, with moderately-long, wavy, scarlet-red hair, and ginger-orange eyes. He is a fully-grown, adult, with a thick, built, muscular physique. He has a heart-shaped hairline, and thick, wavy sideburns. His coat is caramel in color, with light, cream-colored markings around his eyes, mouth, and on his arms. His face is very masculine, with a prominent brow, defined cheekbones, a cleft-chin, a chiseled jaw, and thick, choppy eyebrows. His eyes are large with thick lashes, and black, tear-drop marks on the lower-lids. Like most Thunderians, he has fangs, claws, and slit-pupils.
Lion-O's primary outfit consists of an azure-blue leotard, with blue lining along the shoulder-straps and abdominal-opening. The outfit is heavily exposed, but includes blue boots with white-lining, as well as a thick, blue support-belt, with white-lining, and the Eye of Thundera at the center; the belt also has three rounded-studs on each side of the Eye.
When he arrived on Third Earth he was an adult, he did not have the chance to age naturally, thus he was a child in an adults body. He was immature and headstrong. It took him a long while to mature, it was a very difficult process.
On Third Earth, much like his big-cat namesake, Lion-O had superb strength, endurance and agility. Very handsome, as described by Cheetara. He also had the cunning and skills of a fighter, but, because of the time spent in his capsule, he missed the experiences needed in growing up. Now, acknowledged as the heir to the throne of the ThunderCats, he wields Jaga's legendary Sword of Omens - nce of the Thundertank, the proud machine build by Panthro. Even so, Panthro and Tygra will serve as role models to Lion-O, especially in the first half of the First Season.
In the latter half of the show's first season, Lion-O has to put all that he has learned to use in the "Anointment Trials," which consist of contests of strength, speed, cunning, and intelligence (this last is referred to as "mind-power" in the story arc) against each of the ThunderCats: Panthro, Cheetara, Wilykit and Wilykat, and Tygra respectively (complicating matters for Lion-O is the fact that he is required to be unarmed for the contests; moreover, the rest of the non-participant ThunderCats are not allowed to assist him). The Mutants are at all times a threat to the ThunderCats, and they attempted to interrupt Lion-O's trials —ultimately without success— to take advantage of this last in an effort to leave the ThunderCats leaderless. Lion-O will ultimately triumph over Mumm-Ra in final trial ("The Trial Of Evil") in the heart of the villain's pyramid in which he discovers that Mumm-Ra, like any Egyptian mummy, is dependent upon his own sarcophagus, Lion-O is crowned the true Lord of the ThunderCats in an august ceremony attended by nearly every inhabitant of Third Earth. Interestingly enough, this will not be the end of Mumm-Ra, as established on the following movie, ThunderCats Ho!
In this TV movie, there were three new Thunderians introduced, who had also survived the destruction of Thundera. A massive cast of returning heroes and villains were incorporated into the story to make it the most epic ThunderCats adventure yet produced. Lion-O is still trying to surpass many types of obstacles, from being rescued from a boiling sea water due to the Berserker's ship cannon, then surviving an avalanche made by the new Mutant's machine - The Iron Fist - then falling from the sky from Shiner's cruise starship, later being trapped in Mumm-Ra's mummies trap bandages, and at last ending in Fire Rock Mountain, to have a one-on-one duel against the samurai Hachiman, who was tricked by Mumm-Ra to fight the young leader once more. This was the first time Jaga the Wise directly helped Lion-O since Grune the Destroyer appeared (in fact, this is the second time the sabretooth lion was summoned). Jaga managed to ask for the Star of Thundera, who was entrusted to Lion-O as a medallion, to not be affected by the dangerous Thundrainium. This medallion was taken away by Mumm-Ra, who believed it would give it absolute power, but conversely concluded with the apparent destruction of Mumm-Ra (this is the "second death" of Mumm-Ra, in fact).
The threat of the Lunattacks and The Treasure of ThunderaEdit
A weakened Mumm-Ra asked for the mutants help to free the wicked Lunataks, who where on a lava crust prison. At first, they proved too much for Lion-O, especially Tug Mug's gravity attacks (being one of the few to tear into pieces the Sword of Omens) and Alluro's mind magic spell. But Lion-O had already grown from his past experiences enough to defeat all of these villains, together with the New ThunderCats and Panthro's new vehicles he finally restore peace on Third Earth and finding the Treasure of Thundera on his reconstructed homeplanet, he did indeed mature.