The galaxies in our Universe are not uniformly distributed; most of them are grouped together in groups and clusters (with groups containing up to 50 and clusters several thousand galaxies), and these groups and clusters and some isolated galaxies in turn form even larger structures called superclusters. Interspersed among these superclusters are large voids of space in which few galaxies exist.
Superclusters can range in size up to several 108 light years. No clusters of superclusters are known, but the existence of bigger structures than supercluster is debated. See Large-scale structure of the cosmos for a discussion.
The following is a list of some nearby superclusters.