Oodiscus is an extinct genus of small size (about 2 centimetres (0.79 in)) trilobite, with three known species.

Oodiscus subgranulatus is known from the upper Lower Cambrian of the USA (New York, Griswold Farm) and Canada (Newfoundland).

Oodiscus occurs in association with other Weymouthiidae (Acidiscus, Acimetopus, Analox, Bathydiscus, Bolboparia, Leptochilodiscus, Serrodiscus), and Calodiscus.

[1] Like all Agnostida, Oodiscus is diminutive and the headshield (or cephalon) and tailshield (or pygidium) are of approximately the same size (or isopygous) and outline.

The central raised area of the cephalon (or glabella) is wide (one-third cephalic width), strongly convex, completely unfurrowed except for shallow lateral depressions much to the back.