Was atheism ever a group identity in Greek antiquity? This paper considers the evidence. For classical Athens, the earliest possible context where atheists may have grouped, the evidence is exiguous and uncertain, but it is possible that (as Plato claimed in The Laws) there were groups of intellectuals who defined themselves by their rejection of belief in the gods. It is even possible that they were called atheoi, if the (usually negative) term was reclaimed. For the Hellenistic period, we have stronger evidence, from doxography, that disbelieving philosophers could be treated as a group; but in this case, the group is imagined as a 'virtual network' across time and space, rather than a face-to-face community.