Polar bodies are as diverse as the organisms that produce them. Although in many animals these cells often die following meiotic maturation of the oocyte, in other organisms they are an essential and diverse part of embryonic development. Here we highlight some of this diversity and summarize the evolutionary basis for their utility. Mol. Reprod. Dev. 78:3–8, 2011. © 2010 Wiley-Liss, Inc.