  We explore some of the ramifications arising from superflares on the
evolutionary history of Earth, other planets in the Solar system, and
exoplanets. We propose that the most powerful superflares can serve as
plausible drivers of extinction events, and that their periodicity could
correspond to certain patterns in the terrestrial fossil diversity record. On
the other hand, weaker superflares may play a positive role in enabling the
origin of life through the formation of key organic compounds. Superflares
could also prove to be quite detrimental to the evolution of complex life on
present-day Mars and exoplanets in the habitable zone of M- and K-dwarfs. We
conclude that the risk posed by superflares has not been sufficiently
appreciated, and that humanity might potentially witness a superflare event in
the next $\sim 10^3$ years leading to devastating economic and technological
losses. In light of the many uncertainties and assumptions associated with our
analysis, we recommend that these results should be viewed with due caution.
