In the far future Earth faced a great evil when some of the galaxies worst villains joined forces to rage a war on the United Planets federation. The original Fatal Five consisted of Emerald Empress, Tharok, The Persuader, Mano and Validus.
When the Milky Way Galaxy and Earth's sun were endangered by the mysterious Sun Eater in the latter half of the 30th Century, five of the worst criminals in the galaxy were brought together by the Legion of Super Heroes to help save civilization. The villains assisted the Legionnaires in the destruction of the Sun-Eater, although the final victory was only achieved through the ultimate sacrifice of Ferro Lad.
Although the Fatal Five earned pardons through their actions, they rejected them and banded together to attempt the conquest of the worlds they had saved. During their career, the original Fatal Five proved powerful enough to conquer an entire planet while still trapped in another dimension and they were the arch foes of the Legion.
Later the Emerald Empress decided to remake the team and appeared on a transport ship going to the prison planet Takron-Galtos with several hundred villains to incarcerate. Unimpressed by those there to pick from, the Empress offered a place for Sensor Girl once the Emerald Eye bowed down to its strange impressions of Sensor Girl. However Sensor Girl refused and struck the Empress, making her a mortal enemy. Taking the Persuader with her the Empress departed and later found suitable replacements including Flare, Caress, Mentallla and Mordecai.
The New 52
The Fatal Five will make their new debut in Legion of Super Heroes #18.
In other media
The Fatal Five appeared in JLU on several occasions battling Supergirl and the Legion of Super-Heroes. They also appear in the Legion of Super-Heroes animated series and in this rendition roles are switched around having the Emerald Empress as the leader instead of Tharok.