A line of undead 'zombies' walk through a field in the night in a still from the film, 'Night Of The Living Dead,' directed by George Romero, 1968. The film has been reissued for screenings on the 50th anniversary of its release. Pictorial Parade/Getty Images hide caption
Kim Su-an plays a little girl trying to get to her mother on an ill-fated train. Next Entertainment World hide caption
Kim Dickens, left, as Madison and Cliff Curtis as Travis in a scene from Fear the Walking Dead, which premieres Sunday. Frank Ockenfels/AP hide caption
Glenn Rhee (Steven Yeun) and Maggie Greene (Lauren Cohan) - The Walking Dead - Season 4 Frank Ockenfels 3/AMC/Frank Ockenfels 3/AMC hide caption
World War Z is just the latest pop-culture incarnation of the Zombie Apocalypse. Adam Frank says the zombies keep coming because they're trying to tell us something. MPC/Paramount Pictures hide caption
So sue me! (A "zombie" who came to protest the government in Ljubljana, Slovenia, in February.) Jure Makovec/AFP/Getty Images hide caption
Jonah Lehrer attends a panel discussion in conjunction with the World Science Festival in 2008. Thos Robinson/Getty Images hide caption
Canadian zombies dress for success. (An Occupy Vancouver "Zombie Walk" in October 2011.) Sergei Bachlakov/Xinhua /Landov hide caption
OK, we're pretty sure this isn't real. (A 1012 Halloween-related festival in Georgia.) Erik S. Lesser/EPA /LANDOV hide caption
A Portland, Maine road sign is changed to a zombie warning on Wednesday, Oct. 10, 2012. It originally read "Night work 8 pm-6 am. Expect delays." Jeff Peterson/AP hide caption
Need to lighten up your day? Invite some of these folks. (A "zombie walk" in Stockholm on Aug. 25.) Jonathan Nackstrand/AFP/Getty Images hide caption
We're researchers. May we ask you a few questions? (A "zombie" photographed on Oct. 31, 2010, in San Jose, Costa Rica.) Yuri Cortez/AFP/Getty Images hide caption