A repulsor beam is a type of energy beam or weapon that uses force to move an object rather than energy to destroy it.

The planet-wide defensive systems of Aldea included an immense repulsor beam that could be used to push possible aggressors away. A "small demonstration" of the Aldean beam was given to the USS Enterprise, resulting in the vessel being pushed several light years away, far enough that at maximum warp it took three days for the ship to reach the planet again. (TNG: "When The Bough Breaks")

Wesley Crusher, under the influence of polywater intoxication, once constructed a small repulsor beam from his model tractor beam by modifying its circuits and connecting it to ship power. Later he applied the same modifications to the tractor beam of Enterprise-D to push the ship away from an approaching stellar fragment .(TNG: "The Naked Now")