Monsters came to life at the spooky showing as makeup artists put on a show for their loyal fans.
"It's a complete geek fest and it's so much fun," said Erin Krueger Mekash, a makeup artist for "American Horror Story."
Behind the mask is Alex Ward, who sits for two hours to become a gruesome, scary figure.
"It's one of those things where you either love it or you hate it because it's almost sort of a zen...you sit," he said.
For those that don't want to sit through all the makeup, spooky masks could be worn.
In addition, Hollywood history is well represented - from movie motorcycles to Jose Fernandez, who spent a year creating "Batman" bat suits.
Monsterpalooza President Elio Brodsky created Monsterpalooza eight years ago in Burbank, and it's been so popular it moved to the Pasadena Convention Center this year - which is twice as big.
"The growth of this show shows that people are interested in seeing this stuff up close and personal," he said.
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Monsterpalooza was expected to be open on Saturday and Sunday from 11 a.m. to 6 p.m.