Porcellio dilatatus (Commonly known as the Giant canyon isopod) is a species of woodlouse in the genus Porcellio belonging to the family Porcellionidae. This species is widespread in Europe, and has also been introduced to North America from Western Europe. They are 15 mm long, are brown coloured and striped. As typical for woodlice, they are saprophages, feeding on decaying organic matter, usually from plants.

Pests: The species are considered to be house pests, that can be found in greenhouses, seed boxes, and flower pots.

Subspecies: Five subspecies are recognised:

• Porcellio dilatatus bonadonai Vandel, 1951
• Porcellio dilatatus dilatatus Brandt, 1833
• Porcellio dilatatus flavus Collinge, 1917
• Porcellio dilatatus petiti Vandel, 1951
• Porcellio dilatatus rufobrunneus Collinge, 1918