XCOM: Enemy Unknown Easter egg allows players to bring in the heavy hitters when times are bleakest. PC Gamer points out that certain soldier names will activate "XCOM Heroes," who are pre-designed super soldiers.
Name alterations for soldier unlocks that have worked so far are Sid Meier, Ken Levine, Joe Kelly and Otto Zander. The one caveat for this phenomenal cosmic super soldier creation power is that once these heroes are summoned the achievements for the game will be turned off.
We also concur with PC Gamer's request that you make sure Levine lives, since after saving humanity from aliens we'd appreciate him finishing BioShock: Infinite.