There are a large number of different developers for B&W film. The recent rise of monobath developers not withstanding, if one wants to experiment with various developers there is no end. The so-called staining developers, which are based on either Pyrogallol or Pyrocatechin, have a strong following.
Some claim that Pyro developers give a better negative, with better highlight separation, sharpness and acutance. Some claim modern developers are comparable.
One of the reasons to use staining developers today is to make negatives for two purposes: printing with silver halide papers with visible light, and for printing with alternative processes using UV light, such as Platinum (Pt) or Palladium (Pd) processes. Regular developers tend to produce suitable negatives for one or the other.
The pyrocat-hd website gives a ton of links to formulas to make your own Pyro developer, a list of Pyro developers at Photographer's Formulary. and more.
