Species: Q
Gender: male
Affiliation: Q Continuum

0 is a fictional character, an opponent of the Q Continuum in the Star Trek universe. He appears in the Star Trek The Q Continuum series of novels.

0 was at one time the mentor of the Q who appears in the first episode of Star Trek: The Next Generation. Approximately a half million years prior to the present, Q discovered 0 alone, in another dimensional plane, on the ice of a desolate planet with only faint, distant stars. Q helped him into our universe (despite the Guardian's objections), and in return 0 promised that he would help Q find new uses for his power.

0 is crippled, being unable to move at superluminal speeds (i.e. faster than light), and when the older Q illustrates 0 to Jean-Luc Picard, 0 is represented with a disabled leg. 0 decides to harness the ancient Calamarain (known then as the Coulalakritous) to convey him at superluminal speeds, but the Calamarain resist, and 0 compresses them into a small ball of ice, although Q stops 0 from continuing to compress to the point of a singularity. Because Q was present, the Calamarain developed a hatred of Q.

After 0 had rediscovered some of his confederates — Gorgan, (*) and The One — he went to the Tkon Empire and attempted to engineer civil strife, but the Tkon empress, determined to complete the generations-long project to replace the solar system's dying sun, made gestures to her opponents that ended the warfare. In anger at the Tkon success, 0 caused the sun at the heart of the empire to go supernova and wiped out all but a few small outposts.

This brought the judgement of the Q continuum against 0, so he fled, dragging an increasingly reticent Q with him, but eventually 0 was forced to do battle with four representatives (Q2 of "Déjà Q", Quinn-Q, and Q's future wife) of the Continuum. The battle lasted for millennia, until only one of 0's associates was left. At one point, 0 could have killed one of the Q, but this shocked Q into action, and he was able to arrest 0. Another of his allies, The One, was also captured after three of the Q removed his body, leaving only his head; he would be discovered centuries later by James T. Kirk still imprisoned on the world then known as Sha Ka Ree. The One would be able to leave his imprisonment with his sincere repentance. Failing that, he would remain there until the heat death of the universe.

The Q tried and sentenced 0 for conduct unbecoming a highly advanced entity. The punishment was banishment outside the galaxy without hope of pardon or parole. After the sentence was carried out, the galactic barrier was erected to keep him out until other beings could stand against him without assistance from the Q.

However, shortly after the Q Civil War, Captain Jean-Luc Picard and the USS Enterprise-E attempt, ignorantly, to drill a wormhole through the galactic barrier. Q attempts to stop them, but one Enterprise crew member nonetheless becomes possessed by 0 and lets him through the barrier. Q allies with the Calamarain to chase the now-demented 0 down and successfully banish him again.