Aistopoda (Greek for "[having] not-visible feet") is an order of highly specialised snake-like stegocephalians known from the Carboniferous and Early Permian of Europe and North America, ranging from tiny forms only 5 centimetres (2 in), to nearly 1 metre (3.3 ft) in length.

The primitive form Ophiderpeton has a pattern of dermal bones in the skull similar in respects to the temnospondyls.

But in the advanced genus Phlegethontia the skull is very light and open, reduced to a series of struts supporting the braincase against the lower jaw, just as in snakes, and it is possible that the aistopods filled the same ecological niches in the Paleozoic that snakes do today.

A recent paper described the internal organization of the aistopod head,[2] finding that aïstopods retained many fish-like features of the skull and brain, including a persistent extension of the notochord into the head and an open canal between the pituitary gland and the mouth.

Evolutionary relationships with other early tetrapods remain controversial, as even the earliest aistopod, the Viséan species Lethiscus stocki, was already highly specialised, although its skull was primitive and extremely fishlike.