Psi War is a comic book story arc, taking place in issues of Superman, Superboy, and Action Comics. The story features a war between various powerful entities with psionic powers, against which Superman has no defense.
In the wake of Brainiac's original attack on Metropolis, twenty people are left with dramatically changed brains. They have gained psionic powers, as part of Brainiac's plan to see if humans could serve as vessels for his people - the Coluans. The people thus modified are known as The Twenty.
One of the Twenty, known only as the H.I.V.E. Queen, has set up an organization called "Holistically Integrated Viral Equality", or H.I.V.E., whose aim is to unite the people psionically, by linking them together in a collective mind, in preparation for Brainiac's return. The Queen is a true believer in Brainiac's mission.
H.I.V.E. has also been gathering up anyone it could find with psionic powers, including Hector Hammond and the little boy who would become Doctor Psycho. Psycho would escape, and attempt to manipulate Superboy into allowing him to drain psionic power from the Boy of Steel.