- Rhombic sulfur, also known as α-sulfur, is the stable form of sulfur at room temperature and pressure. It is a pale yellow, crystalline solid with an orthorhombic crystal structure. It has a density of 2.07 g/cm3 and a melting point of 444.6 K (171.5 °C).

- Monoclinic sulfur, also known as β-sulfur, is a metastable form of sulfur that can be obtained by heating rhombic sulfur to a temperature above 368 K (95 °C) and quickly cooling it. It is a yellow, oily liquid with a monoclinic crystal structure. It has a density of 1.96 g/cm3 and a melting point of 392.7 K (119.6 °C).

- Amorphous sulfur is a non-crystalline form of sulfur that can be obtained by rapidly cooling molten sulfur. It is a dark brown, rubbery material with a density of 1.89 g/cm3 and a melting point of 395.3 K (122.2 °C).

- Plastic sulfur is a viscous, semi-solid form of sulfur that can be obtained by heating monoclinic sulfur to a temperature of 159°C. It is a yellow-brown, sticky material with a density of 1.92 g/cm3 and a melting point of 379.6 K (106.5 °C).

Additionally, two liquid forms of sulfur can exist and these are known as:

- S8.

- S6.