Supernova
The catastrophic explosion of a star at the end of its life, briefly outshining an entire galaxy and forging most heavy elements in the universe.
A supernova is a stellar explosion in which a star releases more energy in seconds than the Sun will produce over its entire ~10-billion-year lifetime. Two main types: Type Ia results from a white dwarf accreting matter past the Chandrasekhar limit and detonating; Type II / core-collapse occurs when a massive star (>8 solar masses) exhausts its fuel and gravitationally collapses.
Supernovae are responsible for forging and dispersing most elements heavier than iron — including the calcium in your bones, the iron in your blood, and the gold in jewellery. They also leave behind compact remnants: neutron stars for mid-mass progenitors, and black holes for the largest.
Famous historical supernovae include SN 1054 (Crab Nebula), SN 1572 (Tycho's), and SN 1987A in the Large Magellanic Cloud — the closest observed in modern times.