Thousands of fans infiltrated San Diego this week for Comic-Con, the annual gathering of all things related to the sparling comic boom industry, bringing out everyone from Hollywood A-listers to zealous fans.

Several actors and actresses were out in full force.

Two of the most famous geeks girls to attend , Olivia Munn and Felicia Day, both tweeted about the costumes.

Puttin on my Sailor Moon, Olivia Munn tweeted tweeted. I ♥ Comic-Con. So much. Sailor Moon refers to a Japanese cartoon franchise that invaded the U.S. in the early '90's.

Conan O'Brien made a joke about the smell at Comic-Con. I have arrived @Comic_Con. The air is thick with the smell of Cheetos and celibacy, he wrote.

See the photos below:

Comic-Con 2011 Stars and Freaks Overrun San Diego
Actress Kristen Stewart poses to promote "Breaking Dawn" from the Twilight Saga at Comic Con in San Diego, California July 21, 2011 Reuters
Comic-Con 2011 Stars and Freaks Overrun San Diego
Actor Boo Boo Stewart poses to promote "Breaking Dawn" from the Twilight Saga at Comic Con in San Diego, California July 21, 2011. Reuters
Comic-Con 2011 Stars and Freaks Overrun San Diego
Actress Kristen Stewart poses to promote "Breaking Dawn" from the Twilight Saga at Comic Con in San Diego, California July 21, 2011. Reuters
Comic-Con 2011 Stars and Freaks Overrun San Diego
Actor Robert Pattinson poses to promote "Breaking Dawn" from the Twilight Saga at Comic Con in San Diego, California July 21, 2011. Reuters
Comic-Con 2011 Stars and Freaks Overrun San Diego
Attendees in costume walk the convention floor at Comic Con in San Diego, California July 21, 2011. Reuters
Comic-Con 2011 Stars and Freaks Overrun San Diego
Cast members Justin Timberlake (R) and Amanda Seyfried speak during an interview for their upcoming motion picture "In Time" at Comic Con in San Diego, California July 21, 2011. Reuters
Comic-Con 2011 Stars and Freaks Overrun San Diego
Convention attendee Sarah Parvini looks out from the crowd during the opening day the pop culture convention Comic Con in San Diego, California July 21, 2011. Reuters
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