superstring theory
theory of strings with supersymmetry
type I string theory
theory of strings where left- and right-movers are identified via orientifolding, obtained as IIB string theory with 32 spacetime-filling D9-branes (producing a O(32) gauge group) and a spacetime-filling O9-plane
little string theory
non-gravitational non-local theory in six spacetime dimensions that can be obtained as an effective theory of NS5-branes in the limit in which gravity decouples
type II string theory
10-dimensional string theory with N=2 supersymmetry (32 supercharges), either as N=(2,0) (type IIA) or N=(1,1) (type IIB)