From slithering snakes, to entangling robots, self-deforming (shape changing) active systems display surprising dynamics. This is particularly true when such systems interact with environments or other agents to generate self-propulsion (movement). In this talk, I will discuss a few projects from my group illustrating unexpected effects in individual and collectives of self-deformers. For example, snakes and snake-like robots mechanically “diffract” from fixed environmental heterogeneities, collections of smart-active robots (smarticles) can locomote (and phototax) as a collective despite individual immobility, and geometrically actively entangling ensembles of blackworms and robots can self-propel as a unit to thermo or phototax without centralized control.