Graphene can be biased by electrical gating or by chemical doping, which modifies its Fermi level and enables the existence of surface plasmons propagating along graphene. These surface plasmons, because of the two-dimensional (2D) nature of this material, have very short wavelengths and extreme out-of-plane confinement. Graphene plasmons feature in the THz regime with relatively low losses, where the plasmonic response of metals is weak. These facts, added to the important ingredient of tunability with external bias, make graphene a very suitable platform for the design of plasmonic metasurfaces in the THz regime. Metasurfaces, which are the 2D counterpart of metamaterials, consist of a planar arrangement of resonant subwavelengthsize building blocks. By appropriately them, metasurfaces provide an ultrathin platform for manipulating electromagnetic waves, and they have shown novel phenomena and applications as from broadband light bending and anomalous reflection and refraction.