Aaron Cassidy is an American composer and conductor based in the UK. His music is gaining increasingly widespread exposure, with recent performances in the United States, Mexico, Canada, Austria, the Netherlands, Croatia, England, France, Sweden, Switzerland, Germany, Portugal, Poland, Thailand, New Zealand, and Australia.

His music can be characterized by an uncompromising dedication to instability and fragmentation. The received wisdom of performance practice is continually questioned and reasserted, often with intentionally unpredictable results. His recent works have experimented largely with the interaction of a performer with his/her instrument, introducing a decoupling of component performance techniques through a variety of extended tablature notations. Fracture is prioritized in timbral, structural, and rhythmic strata in such a way that resulting aural units are themselves only the byproducts or collisions of independent (and often cyclic) musical processes. The musical score becomes, then, both the locus of processual sediment and concurrently the cause of significant deterritorialization on the part of performer and listener alike.

Recent projects have included significant research of linguistic, semantic, and spatial theories, focusing in particular on heightened states of dislocation (as in Jakobson's analysis of aphasics or Deleuze and Guattari's writings on smooth and haptic space).