Supernovae are tied to neutron stars as they are the explosive events that create them. They are so powerful because the star has lost the fight against gravity, and it ends up exploding! Superluminous supernovae are thought to be so luminous due to a magnetar being the power source of the excess emission.
Also, some gamma-ray bursts occur when a neutron star collides with another neutron star or possibly a black hole! These events are so powerful because they involve ripping apart a neutron star and colliding two very massive and dense objects together.
Some fast radio bursts are also connected to neutron stars, as we've detected a fast radio burst from a neutron star, specifically a magnetar, within our own galaxy. So overall, neutron stars are quite ubiquitous among many transients that we can observe.