Iron sulfide or Iron sulphide can refer to range of chemical compounds composed of iron and sulfur.

Minerals

By increasing order of stability:

• Iron(II) sulfide, FeS
• Greigite, Fe₃S₄ (cubic)
• Pyrrhotite, Fe_1−xS (where x = 0 to 0.2) (monoclinic or hexagonal)
• Troilite, FeS, the endmember of pyrrhotite (hexagonal)
• Mackinawite, Fe_1+xS (where x = 0 to 0.1) (tetragonal)
• Marcasite, orthorhombic FeS₂
• Pyrite, cubic FeS₂ (fool's gold)
• Arsenopyrite (mispickel), FeAsS, or Fe(As-S), Fe(III) mixed arseno-sulfide (monoclinic)

Synthetic

• Iron(III) sulfide, Fe₂S₃
• Iron-sulfur clusters, includes both synthetic and biological

Biological

• Iron–sulfur protein