Armus
Armus is an amorphous entity that appears in the TNG episode "Skin of Evil". It dwelled on the planet Vagra III, which it hoped to escape on the USS Enterprise. It claimed to have formed from the negative psychic energy of the planet's original habitants, who had cast off their undesired personality traits before departing from the planet.
Attributes
Armus was a pool of black fluid several meters in diameter, resembling a large puddle of tar. It could move easily by flowing over the planet's surface. I could also raise a humanoid shape out of its mass.
Armus had telekinetic abilities at least sufficient to drag a human being over the planet's surface against his will. It used an energy attack of an unknown nature to kill Tasha Yar, doing little physical damage but leaving her completely unrevivable by Federation medical technology. It engulfed Commander Riker and held him inside is mass for an extended period of time without either suffering lasting harm. It generated a force field of an unspecified nature that blocked communications and transporter functions. It could also withstand simultaneous fire from at least two hand phasers with no apparent effect. Its most impressive feat, however, was forcing a passing shuttlecraft to crash land on its planet.
One of the creature's numerous personality flaws was self-loathing, and its force fields and other abilities declined in strength when it was forced to confront these feelings. Captain Picard was able to trick Armus into just such an introspection, allowing the Enterprise to rescue its away team.
Before departing, the Enterprise fired a photon torpedo at the planets surface to destroy the damaged shuttlecraft, hoping to make sure that Armus did not somehow restore the shuttle enough to use it as an escape vessel. Whether the torpedo detonation had any effect on Armus itself is unknown.