Eight-spotted Crab Spider
Platythomisus octomaculatus is one of the most festive-looking spiders around. With a bright yellow body and black spots, it looks almost as if it's dressing up as a ladybug for Halloween [source: Wired].
Discovered in a forest preserve in Singapore in 1924, this spider lives in the foliage of small trees and has been observed only sporadically ever since. It's one of the biggest types of crab spiders, at about 1 inch (2.5 centimeters) in length. Today, scientists believe its existence may be threatened by disturbances to its habitat [source: Singapore Red Data Book].