TON 618 is a hyperluminous, broad-emission-line, radio-loud quasar, and Lyman-alpha blob located near the border of the constellations Canes Venatici and Coma Berenices, with the projected comoving distance of approximately 18.2 billion light-years from Earth. It contains one of the most massive black holes ever found, at roughly 40.7 billion times the Sun's mass (M☉), though some older, more frequently-cited estimates yield 66 billion M☉.