Krall

Krall was an apparently alien warlord in the. However, Krall was once Balthazar M. Edison, a former MACO major and Federation Starfleet captain of the USS Franklin (NX-326), and a Human by birth (his reptilian appearance was due to a life-extension technology he used). He was then listed as "Missing In Action".

Biography
Born in the 22nd century, Balthazar M. Edison entered United Earth's Military Assault Command Operations. He rose through the ranks, becoming a Major in the 2150s. Edison fought against both the Xindi in the Xindi incident and then the Romulans in the Earth-Romulan War of 2156 through 2160.

A year after the war ended the United Federation of Planets was formed. At that time the MACOs were absorbed in to Starfleet. Edison was given a Starfleet commission of Captain and in 2163 was assigned to command the USS Franklin (NX-326) - which had been the first Starfleet vessel to reach warp 4.

What Starfleet did not realize was that Edison harbored deep resentment over being put out to pasture, and after the Franklin crash landed on the planet Altamid he and some of the other survivors came to believe that Starfleet had abandoned them. Descending into madness he and the other survivors came to despise the Federation for its policy of peaceful cooperation.