Hydrogen sulfide generation is one of the key detriments linked to microbial activity in the oil and gas industry and is the most likely cause of most microbiologically influenced corrosion. H2S is extremely corrosive to most metals and can significantly devalue produced fluids and gases as well as raise HS&E concerns for production facilities. Microbial sulfidogenesis has historically been linked to only a few types of sulfate reducing bacteria that are capable of growth in Modified Postgate’s B medium but recent advances in microbial identification techniques have shown that the sulfide generating population in the industry is made up of over 140 different genera. Metabolic studies have shown that the vast majority of these microbes require thiosulfate elemental sulfur (bi)sulfite and other sulfur compounds for energy production and can therefore not be cultured using standard oilfield methods. This paper discusses the prevalence and distribution of the varied population of sulfide generating bacteria and archaea that have been identified by DNA sequencing from over 7000 samples obtained from numerous sites throughout hydrocarbon production facilities found all over the world.