Neo Megas were the first sub-brood of baseline Neosapiens, designed with heightened intellect, to be created by Phaeton's leading genetic specialist, Praetorius.
Visually, the Neo Megas resembled very thin and small Neosapiens with disproportionately large heads. Their hands had only three fingers, and their feet had only three toes. They were able to communicate with one another via high frequency sounds and enter a coma-like state at will. Some sources indicate that the first Neo Mega breeding facility was located on Ceres.
Apparently not convinced by his generals' intellectual abilities, Phaeton assigned a Neo Mega (in some cases, even two) to each of them as advisors and observers. Another reason for their creation was likely the failure of the Alpha Neosapiens in "Scorched Venus" and "Behind the Shield".
However, the Neo Megas were never content with their advisory role and made numerous attempts to rise to power. Part of their strategy was to undermine the authority of the Neosapien generals, such as Shiva and Draconis. The generals were excluded from the Neo Mega's plans and were always treated as inferior.
Their last chance was an unsuccessful coup d'état, when they combined their efforts with Marsala's in an attempt to assassinate Phaeton and seize power for themselves. To convince him to cooperate, Marsala was told that the plan was only to kidnap Phaeton and then declare ceasefire and, eventually, peace with Terrans. In fact, that was the plan proposed by Praetorius' advisor Galba, but other Neo Megas, who believed that no peace between the two races could be achieved, have soon silenced him by throwing him into prison. That is why, after Marsala failed his mission and Phaeton personally ordered the entire Neo Mega race to be executed en-masse; Galba became the sole remaining Neo Mega in the universe, although, Sulla, who was captured in "The Dogs of War", may have also survived the Neosapien War.