Observational work conducted over the last few decades indicates that all massive galaxies have supermassive black holes at their centres .
Although the luminosities and brightness fluctuations of quasars in the early Universe suggest that some are powered by black holes with masses greater than 10 billion solar masses [ 2 , 3 ] , the remnants of these objects have not been found in the nearby Universe .
The giant elliptical galaxy Messier 87 hosts the hitherto most massive known black hole , which has a mass of 6.3 billion solar masses [ 4 , 5 ] .
Here we report that NGC 3842 , the brightest galaxy in a cluster at a distance from Earth of 98 megaparsecs , has a central black hole with a mass of 9.7 billion solar masses , and that a black hole of comparable or greater mass is present in NGC 4889 , the brightest galaxy in the Coma cluster ( at a distance of 103 megaparsecs ) .
These two black holes are significantly more massive than predicted by linearly extrapolating the widely-used correlations between black hole mass and the stellar velocity dispersion or bulge luminosity of the host galaxy [ 6 , 7 , 8 , 9 , 10 ] .
Although these correlations remain useful for predicting black hole masses in less massive elliptical galaxies , our measurements suggest that different evolutionary processes influence the growth of the largest galaxies and their black holes .