With the use of graphene as a model system, this thesis primarily explores the use of topological (ring) defects in a 2D system, from their formation during growth to their physical and electronic effects.  Specifically, the work encompasses how a ring defect at the growth edge of a 2D system can induce significant further defects, how a lattice of sparse ring defects (disclinations) can affect the physical shape of a system and admit significant reconfigurability, and how the detailed spacing of ring defects affects the DOS of graphene, including controlling gapping or metallicity.