Rhysida is a large genus of Scolopendromorph centipedes in the subfamily Otostigminae. It is the second largest genus in the subfamily Otostigminae, with species found in the Neotropics, Indo-Malaya, and Africa. It shares some morphological characteristics with the genus Alluropus, and its phylogeny in the subfamily Otostigminae is somewhat uncertain.

Centipedes are predatory arthropods belonging to the class Chilopoda of the subphylum Myriapoda, an arthropod group which includes millipedes and other multi-legged animals. Centipedes are elongated segmented (metameric) creatures with one pair of legs per body segment. All centipedes are venomous and can inflict painful stings, injecting their venom through pincer-like appendages known as forcipules or toxicognaths, which are actually modified legs instead of fangs. Despite the name, no centipede has exactly 100 pairs of legs; the number of pairs of legs is an odd number that ranges from 15 pairs to 191 pairs.