The Demon Miners are demonic entities who served The Collector.
The Demon Miners are blue goblin-like entities that dress as construction workers, complete with a pick axe and search helmet. They work to expand an extra-dimensional hole that allows objects to be drawn into the Land of Lost Objects.
In recent times, the diggers appeared at a dig site in Brooklyn. They felt threatened by Ed Zeddemore's efforts to plug up the hole and tried to defend it. Luckily, the Ghostbusters arrived and pushed them back with the Proton Streams. The diggers continued to expand the hole undaunted. Peter Venkman referred to them as "strange blue puppies."