A small group of protists with filose pseudopods and lacking shells. Vampyrella is typical of the group. When free-floating the cell is spherical and around 30 μm across, with long radially directed filose pseudopods as well as distinctive shorter club-shaped ones, so that it resembles a heliozoan. Moving, the cell stretches out and takes a more typical amoeboid form, with an obvious distinction between the clear periphery and pseudopods and the greenish interior. In this form it finds its way into algae cells and feeds on their interiors. A few other vampyrellids are parasitic on fungi.

Vampyrellids characteristically have mitochondria with tubular cristae. Together with the nucleariids they include the majority of the naked filose amoebae.