Black holes have been found, that is candidates for them, mostly near binary systems. Cygnus X-1 is a candidate. The largest, thought, black holes, are supermassive black holes that weight at 10 to the sixth and to the ninth solar masses. These massive objects are thought to exist at the center of galaxies. These give rise to the quasar phenomenon.
Black holes do and can get small.
A pulsar is a regularly pulsing object that gives off radiation and is the origination spot for neutron stars. They were first found at radio wavelengths but now they are found at optical and gamma ray wavelengths. Almost all pulsars are single stars, even binary pulsars don't share their emissions. Within our galaxy, the Milky Way, has over a million pulsars, and is estimated that around to more than 25 form per century. Pulsars and some black holes are though to originate form supernovas.