Malachi was a minor Centauri hero introduced in the Babylon 5 episode The Coming of Shadows.
He was played by Malachi Throne, who had played the Keeper, Jose I. Mendez, and Pardek in Star Trek media.
As Londo Mollari came of age in the Centauri royal court, Malachi and Londo became good friends.
A close personal friend of Emperor Turhan, Malachi served as prime minister for the Centauri Republic in 2259. He knew that Turhan's health was failing, and tried to dissuade the Emperor from travelling to Babylon 5. The Emperor, however, was insistent and left Malachi in charge of things at home.
Due to the telepathic link between Turhan's wives at home and on B5, Malachi was immediately informed when Turhan had a massive heart attack on B5. Knowing that Turhan would probably soon be dead, Malachi steeled himself for the difficult days ahead when it came time to find a successor for Turhan. This was vital since with the death of the Emperor's son earlier there was no clear line of succession.
Knowing that Malachi could block his faction from seizing power, Lord Antono Refa arranged for Malachi to be murdered. Without Malachi to block Refa, he and his allies were able to install Turhan's nephew Cartagia as the next Emperor.
A year after Malachi's death Londo cited the murder of Malachi by Refa's men as a reason for seeking revenge against Refa. Malachi's murder was avenged when Refa died on the Narn homeworld.