Starbusters

A "Starbuster" is a character or weapon which has the capability to destroy a star, or produce an attack equal to an exploding star.

"Starbuster" is the next step up from a planetbuster, and in reality, would follow the same principal of gravitational binding energy to perform. Being a "Starbuster", like a planetbuster, would at the minimum conform to destruction of a star by overcoming its gravitational binding energy.

For our own Sun, the energy needed is actually 6.87xE41 joules or around 164.913 tenatons, and that is over 3 billion times the energy required for earth.

However, the Sun is actually larger and brighter than most stars in the visible universe, and the sizes of stars vary greatly (much like planets). For this reason, there are two other sub-categories in the general "Star busting" range.

Small:  This is the energy required to destroy the smallest stars, which are red dwarves many times smaller than the Sun. This would require around 2.998 tenatons.

Large:  This sub-category corresponds to the most massive stars - blue giants. A typical star like Rigel (used as the benchmark here) has a gravitational binding energy of around 330.544 tenatons.

In fiction, "Starbusters" come in two types: those which equal the power of an exploding star/can destroy a star, or those which achieve it by chain reaction/non brute force. A "Starbuster" of the direct variety would be considered much more powerful, since they can bring the energy of a star to bear as a destructive attack anywhere, whereas a device which causes a star to become unstable, requires that the device is deployed to the star in order to work, and it's actual destructive power is nowhere near enough as it is.

The next step up from a "Starbuster" would be destroying entire star systems/clusters, and then even galaxies.