  This is an introduction to the special issue titled "Collective behavior and
evolutionary games" that is in the making at Chaos, Solitons & Fractals. The
term collective behavior covers many different phenomena in nature and society.
From bird flocks and fish swarms to social movements and herding effects, it is
the lack of a central planner that makes the spontaneous emergence of sometimes
beautifully ordered and seemingly meticulously designed behavior all the more
sensational and intriguing. The goal of the special issue is to attract
submissions that identify unifying principles that describe the essential
aspects of collective behavior, and which thus allow for a better
interpretation and foster the understanding of the complexity arising in such
systems. As the title of the special issue suggests, the later may come from
the realm of evolutionary games, but this is certainly not a necessity, neither
for this special issue, and certainly not in general. Interdisciplinary work on
all aspects of collective behavior, regardless of background and motivation,
and including synchronization and human cognition, is very welcome.
