Bronteroc
The very embodiment of a keystone species, the bronteroc is essential if life is to survive on a planet. The diet of bronterocs is composed of oiligarchs, social, political, and financial aristocrats, and other "takers". Without bronterocs to consume them this upper crust will smother the apple pie of life on a planet resulting in the eventual destruction of all multicellular life on the planet.
As beautiful as it is useful if the bronteroc does not evolve on a planet eventually another species will develop which will cause the destruction of the planet's biodiversity through rapacious plunder.