N'Grath was a criminal kingpin operating out of Babylon 5's Down Below under the very thin pretext of a legitimate businessman. A member of a non-oxygen breathing, bipedal insectoid race, N'Grath rarely left his quarters in the alien sector, preferring instead for business to come to him.
In early March 2258, a rogue Soul Hunter escaped custody; he came to N'Grath seeking information on the layout of Babylon 5 and a way to get into Green Sector. N'Grath was able to sell him a Level 5 Security Pass.
Later that month when G'Kar learned an old political enemy had arranged for a Narn assassin, he came to N'Grath to hire a bodyguard. N'Grath mocked that "the mighty Narn Empire" could not protect its ambassador, but did supply a bodyguard. G'Kar was pleased, but the thug was soon murdered by the assassin.
In May of that year when Michael Garibaldi was framed for a bombing in one of the docking bays, he goes on the run to try and prove his innocence. He comes to N'Grath to try and get some help, but N'Grath insists he is an honest businessman and will not deal with "police."
At some point prior to 2262, N'Grath was taken down, leaving a power vacuum in B5's underworld and allowing small-time operators like Deuce take over half of the rackets in Downbelow and former Beta VII criminal Trace to vie for control.