Titus Rikka was the alias assumed by a renegade Changeling posing as a Human on M'talas Prime. According to Starfleet records, he had multiple contacts with the criminal underworld.
In 2401, Rikka paid the Ferengi crime lord Sneed to frame Lurak T'Luco for the terrorist attack on the Starfleet recruitment center in District Seven. Upon learning of this, Worf and Commander Raffaela Musiker captured him in District Six and brought him to SS La Sirena for interrogation. The only useful information Rikka divulged was that he and other "enemies of the Federation" had broken into Daystrom Station and stolen quantum tunneling technology as a diversion. All the while, he displayed acute physical distress that Musiker misinterpreted as the symptoms of drug withdrawal.
However, Rikka eventually began to involuntarily shapeshift under the strain of maintaining a solid shape for too long. Now exposed as a Changeling, Rikka taunted his captors that it was too late to stop their plans against the Federation, before reverting to his liquid state and slipping his bonds. To prevent his escape, Worf vaporized him with a type 2 phaser. (PIC: "Seventeen Seconds")
Rikka's file was among the data collected by Commander Ro Laren pertaining to the Changeling infiltration of Starfleet, which she passed to Admiral Jean-Luc Picard shortly before her death. (PIC: "Imposters")
Titus Rikka was portrayed by Thomas Dekker.