Stacking interactions of terpyridyl square-planar complexes in crystal structures were studied analyzing data from the Cambridge Structural Database. In most of the crystal structures, two terpyridyl complexes were oriented “head-to-tail” or “head-to-head”, with “head-to-tail orientation” being most prevalent. The number of structures with other orientations was very small. Based on the analysis of interacting geometries, we classified overlaps of terpyridyl complexes into six types. The types were defined by values of several geometrical parameters and all interactions of the same type had very similar overlap patterns.