There is an extinction scenario that human kind has not paid enough attention to: gamma-ray bursts.
To astronomers, gamma-ray bursts (GRBs) are among the most energetic and explosive events in the universe. They are incredibly energetic but short-lived explosions, lasting from a few milliseconds to about a minute.
All GRBs observed so far occurred in distant galaxies. The intense radiation from GRBs could originate from a supernova, high-mass star collapses to form a neutron star, quark star, or black hole.
According to a study published in Nature in July 2017, an international team of astronomers constructed one of the most detailed descriptions of a gamma-ray burst (known as GRB160625B) to date, using a wide array of ground- and space-based telescope observations.
A nearby GRB event, say at the distance of a few parsec (one parsec equals to about 2e+13 miles or 3e+13 kilometers) away from Earth, can create toxic chemical products in our atmosphere and also raise the UV radiation to life-damaging level.
Source: PBS Space Time via Youtube