Mon'el
Mon'el aka Valor
Mon'el is hero of the Legion of Superheroes. He is also one of the one's that has undergone the most drastic changes with the changes between reboots.
The original Mon'el was introduced in a story that had him believe he was actually Superman's older brother from Krypton. In actuality, he was a a Daxamite space traveller who'd merely briefly stopped on Krypton before Jor-el had given him directions off planet. Because Daxamites suffer permanent body damage from lead fragments entering their body, Mon'el was nearly killed upon his arrival to Earth. Superboy then placed Mon'el in the Phantom Zone where he hoped to release him after a cure was found.
The psychological ramifications of spending 1,000 years in a Purgatory that has been likened to Hell itself were never fully explored in any of his incarnations but it remains present in all of his origin stories. It was suggested that he had an understandable fear of returning to the nightmarish dimension and the only reason he remained sane was the awareness that he wasn't here for any crime.
In the 30th century though, Mon'el was freed by Superboy and the Legion of Superheroes who offered him a home in that time. Mon'el joined and spent many adventures in the Legion as their most powerful member after Superboy and Supergirl. He arguably was stronger due to the fact that he was not vulnerable to Kryptonite or Red Sunlight due to a special formula he took that also cured his lead weakness.
Mon'el's personality was one of the more subdued of the Legions. A educated explorer who kept his own counsel and was friendly in a distant way, he did not have anyone particularly close to him except for Shadow Lass who became his lover before eventually becoming his wife. Mon'els only other close friend seemed to be Superboy whom he joined the quest to avenge when the Pocket Universe hero was killed by the Time Trapper.
The reprocussions for Mon'els victory would have fairly drastic consequences as he was forced into several bizaree time travel adventures. One of the after effects of the Time Trapper's death and Glorith's meddling was the transformation of Mon'el from a lost Daxamite to a massively revered figure that was treated as a god. He even became the hero that inspired the Legion rather than the man that he avenged the death of. Mon'el remained humble and refused to allow this.
Mon'el died unknown to the Legion (actually before he avenged Superboy but the peculiarities of his death are difficult to describe) when he had his 'soul' replaced by his many great nephew Eltros. Eltros was overwhelmed by Mon'el's memories and believed himself to be him until Zero Hour when he dissappeared with the rest of the victims of Parallax.
Reboot
Mon'el was the son of a Daxamite Explorer who died in the Invasion of Earth by the Khund, Dominator, and Thanagarian alliance. Wishing to know what happened to his father, he travelled and joined L.E.G.I.O.N, where he quickly established himself as the most powerful member of the organization. Mon'el's gentle nature contrasted horribly with the megalomanical Vril Dox the Second's though and he soon left.
Mon'el's heroism in the 20th century includes single handidly thwarting a second Dominator invasion of Earth, settling many human being prisoners on M-class planets that he'd discovered on his journeys, and generally acting as a superhero might to the galaxy at large. Because the human beings lacked much in the way of technology, they used their distant memories to raise 'Valor' up as a god.
Eventually, he made his way to Earth where lead poisoning overtook him and the second Superboy Kon'el saved his life by putting him in a 'Stasis Zone' (unknown to him, the Post-Crisis Phantom Zone). Mon'el continued his 1000 year dwelling, possibly encountering Kandor or the False Krypton inside his Hellish Prison.
When he emerged in the 30th century, he once more joined the Legion of Superheroes and was surprisingly joined by his distant niece Andromeda.
Threeboot
Mon'el has yet to show up in the Threeboot but still exists in the mainstream DCU continuity by his appearence in the Phantom Zone during the "Return to Krypton" arc.