Introduction: The Universe's Celebrities

Among the billions of black holes that populate the universe, a few have achieved fame. They are the first to be photographed, the ones that reveal secrets about our galaxy, the ones that break records for mass or speed, and the ones that have taught us the most about gravity, spacetime, and the evolution of the cosmos. These famous black holes are not just scientific curiosities; they are cosmic landmarks that have shaped our understanding of the universe. This article profiles the most renowned black holes discovered to date, from the one at the heart of our own galaxy to the most distant quasar-powered behemoth ever found.

Sagittarius A*: The Heart of the Milky Way

At the very center of our galaxy, 26,000 light-years from Earth, lies Sagittarius A* (pronounced "Sagittarius A-star"), the supermassive black hole that anchors the Milky Way. With a mass of about 4 million Suns, it is modest by supermassive standards, but its proximity makes it the most studied black hole in the universe .

For decades, astronomers inferred its existence by tracking the orbits of stars around it. The star S2 completes a 16-year orbit, coming within 17 light-hours of the invisible object—about four times the distance of Neptune from the Sun. At closest approach, it travels at 3% of the speed of light . These observations, led by Reinhard Genzel and Andrea Ghez, earned them the 2020 Nobel Prize in Physics .

On May 12, 2022, the Event Horizon Telescope released the first image of Sagittarius A*'s shadow. The image shows a dark central region surrounded by a bright ring of light, matching the predictions of General Relativity. The ring is about 50 microarcseconds across—equivalent to seeing a donut on the moon from Earth . Unlike the stable image of M87's black hole, Sagittarius A* varies on timescales of minutes, as material orbits the smaller black hole rapidly. Capturing its image required averaging thousands of snapshots and developing new algorithms to account for the variability .

Sagittarius A* is surprisingly quiet. It accretes very little matter, making it hundreds of times fainter than it could be. Occasionally, it flares as it swallows a gas cloud or asteroid, but compared to active galactic nuclei, it's a sleeping giant. Studying it teaches us about the quiescent phase of supermassive black hole life .

M87: The First Black Hole Ever Photographed

On April 10, 2019, the world saw its first image of a black hole. The subject was the supermassive black hole at the center of galaxy M87 (Messier 87), a giant elliptical galaxy 55 million light-years away in the Virgo cluster . With a mass of 6.5 billion Suns, it is one of the most massive black holes known .

The image shows a dark shadow surrounded by a lopsided, bright ring. The ring is brighter on one side due to Doppler beaming—material in the accretion disk moving toward us appears brighter, while material moving away appears dimmer. This asymmetry confirms that the black hole is rotating and that we are viewing it from an angle .

M87's black hole is famous for another reason: it launches a spectacular jet of plasma that extends for 5,000 light-years. This jet, visible in optical and radio images, was first observed in 1918, long before anyone knew what caused it. The black hole's spin and magnetic fields accelerate particles to near-light speed, creating one of the most powerful and persistent cosmic phenomena . The Event Horizon Telescope observations are now being combined with other telescopes to study how the jet is launched from the immediate vicinity of the black hole.

Unlike Sagittarius A*, M87's black hole is stable on human timescales. Its enormous size means that material takes days or weeks to orbit, making it an easier target for imaging. Future observations with more telescopes will produce movies of its accretion flow .

TON 618: The Brightest Quasar

If you want power, look to TON 618. First cataloged in 1957 as a faint blue star in the constellation Canes Venatici, it was later identified as a quasar over 10 billion light-years away . A quasar is an active galactic nucleus where a supermassive black hole is accreting matter so rapidly that it outshines all the stars in its host galaxy.

The black hole powering TON 618 is estimated to have a mass of about 66 billion Suns , making it one of the most massive black holes ever discovered. Its event horizon would be about 1,300 astronomical units across—40 times the orbital distance of Neptune. Its luminosity is equivalent to 140 trillion Suns, making it one of the brightest objects in the observable universe .

TON 618 is a quasar, meaning we see it as it was when the universe was about 3 billion years old—a time when black holes were growing rapidly. It represents the extreme end of black hole growth: how could any object become so massive so quickly? This question drives research into the formation and evolution of supermassive black holes .

The name "TON" comes from the Tonantzintla Observatory in Mexico, where it was first cataloged. Despite its immense distance and luminosity, it appears as a faint point of light in optical telescopes, its true nature revealed only through spectroscopy .

Cygnus X-1: The First Confirmed Black Hole

Long before we imaged black holes or detected their mergers, we had Cygnus X-1. Discovered in 1964 by detectors flown on sounding rockets, it was one of the first X-ray sources found in the constellation Cygnus . In the 1970s, astronomers identified its optical counterpart—a blue supergiant star named HDE 226868—orbiting an invisible companion with a period of 5.6 days .

By measuring the star's orbit, astronomers calculated that the invisible object has a mass of about 21 Suns . This is far above the maximum mass for a neutron star (about 3 Suns), so the companion must be a black hole. This made Cygnus X-1 the first widely accepted black hole candidate .

The discovery was not without controversy. A friendly bet between Stephen Hawking and Kip Thorne famously wagered whether Cygnus X-1 actually contained a black hole. Hawking conceded in 1990 when observational evidence became overwhelming, paying Thorne with a subscription to Penthouse magazine .

Cygnus X-1 is a microquasar, launching jets that produce radio emission. It has been observed across the spectrum, from radio to gamma rays, and continues to be a target for studying accretion physics. In 2021, a new analysis of parallax data from the Very Long Baseline Array refined its distance to about 7,200 light-years and its mass to 21 Suns, confirming it as one of the most massive stellar-mass black holes known .

GW150914: The First Gravitational Wave Source

On September 14, 2015, humanity heard the universe for the first time. GW150914 was the first direct detection of gravitational waves, ripples in spacetime predicted by Einstein a century earlier . The signal came from the merger of two black holes 1.3 billion light-years away.

The two black holes had masses of about 36 and 29 Suns. They spiraled together, emitting gravitational waves, and merged into a single black hole of 62 Suns. The remaining 3 Suns of mass were converted directly into energy in the form of gravitational waves—more energy than all the stars in the observable universe emit in that fraction of a second .

The detection, made by the twin LIGO observatories, earned the 2017 Nobel Prize in Physics for Rainer Weiss, Barry Barish, and Kip Thorne . It proved that black hole binaries exist, that they merge, and that gravitational waves can be detected. Since then, LIGO and its partners Virgo and KAGRA have detected nearly 100 such events .

GW150914 is famous not for being the biggest or the closest, but for being the first. It opened gravitational wave astronomy, providing a new way to study black holes that is not blocked by dust and does not depend on light.

Gaia BH1: The Closest Black Hole to Earth

For decades, the title of "closest known black hole" bounced between candidates, but in 2022, the Gaia spacecraft delivered a definitive answer. Gaia BH1 is a dormant black hole just 1,560 light-years away in the constellation Ophiuchus .

What makes Gaia BH1 special is its companion: a Sun-like star in a 185-day orbit around an invisible object. From the star's motion, astronomers calculated that the unseen companion has a mass of about 10 Suns—too massive for a neutron star. Yet there is no sign of accretion: no X-rays, no radio emission, no glowing disk. The black hole is truly dormant, completely invisible except for its gravitational influence .

This is the first unambiguous detection of a dormant stellar-mass black hole. Most black holes are found when they're actively accreting, but the majority should be dormant. Gaia BH1 provides a template for finding them. Gaia is expected to discover dozens more as its mission continues, revealing the true population of black holes in our galaxy .

The system is so clean that it challenges formation models. How did the Sun-like star survive the supernova that created the black hole? The orbit is too tight for a standard binary evolution scenario, suggesting that the black hole might have formed through direct collapse without a supernova, or that the system underwent complex interactions .

OJ 287: The Binary Black Hole

OJ 287 is a blazar—an active galactic nucleus with a jet pointed almost directly at Earth—located 3.5 billion light-years away. But what makes it famous is that it likely contains two supermassive black holes orbiting each other .

The system shows regular outbursts every 12 years, but with a peculiar pattern: two outbursts per period, separated by about one year. This pattern is best explained by a secondary black hole plowing through the accretion disk of the primary, causing two flashes per orbit .

The primary black hole has a mass of about 18 billion Suns, making it one of the most massive known. The secondary weighs in at about 150 million Suns and orbits the primary with a period of 12 years . Their orbit is precessing due to relativistic effects, providing a testbed for General Relativity in strong gravity.

OJ 287 is a target for future gravitational wave observatories like LISA, which could detect the low-frequency waves from such a binary. It also demonstrates that supermassive black holes can exist in binaries, a precursor to the mergers that LISA will detect across the universe .

Phoenix A and Abell 1201: The Record Holders

The title of "most massive black hole" is contested, but two stand out:

Phoenix A: At the center of the Phoenix Cluster, about 8.5 billion light-years away, lies a black hole with an estimated mass of 100 billion Suns . Its event horizon would be about 590 billion kilometers across—100 times the distance from the Sun to Pluto. It is growing rapidly, consuming about 60 Suns worth of material each year, and its host cluster has one of the highest star formation rates ever observed .

Abell 1201: In February 2026, astronomers announced the discovery of an ultramassive black hole at the center of galaxy Abell 1201, about 2 billion light-years away . Using gravitational lensing, they estimated its mass at more than 30 billion Suns. While smaller than Phoenix A, it is significant as the first black hole discovered solely through gravitational lensing, a technique that will find many more .

These ultramassive black holes push the limits of theory. How do they grow so large? There may be an upper limit around 100 billion Suns, beyond which accretion disks become unstable and fragment into stars, starving the black hole .

Conclusion: The Universe's All-Stars

From the quiet giant at our galaxy's center to the brightest quasar in the early universe, from the first confirmed black hole to the first gravitational wave source, these famous black holes have shaped our understanding of the cosmos. Each tells a different story: how black holes form, how they grow, how they interact with their environments, and how they die. They have been observed across the electromagnetic spectrum and, in one case, through gravitational waves. Their shadows have been imaged, their masses weighed, their spins measured.

As new observatories come online—the Vera C. Rubin Observatory, the James Webb Space Telescope, the Nancy Grace Roman Space Telescope, and next-generation gravitational wave detectors—the roster of famous black holes will grow. But these pioneers will always hold a special place in the history of astronomy. They are the ones that taught us that black holes are real, that they exist in abundance, and that they play a fundamental role in shaping the universe.