There was some hope at one point that something like the LHC might produce black holes, but not the type you're thinking of as massive gravity wells that form when stars collapse. It has been postulated that the early universe in the immediate aftermath of the Big Bang may have contained primordial black holes, and any that were large enough to still exist today might be a possible source of dark matter. Any formed in a particle collider would be particle mass, not star mass, and have the gravitational attraction of particles, and evaporate almost instantly due to Hawking radiation. They'd have been harmless, but if it had been possible, it would at least confirm they actually can exist and observing the decay would have been our only realistic hope of observing Hawking radiation likely at least in this century.
