The quantum states in small, compact metal clusters are bunched into electronic shells with electronic orbitals resembling those in atoms, enabling classification of stable clusters as superatoms. The filling of superatomic orbitals, however, does not generally follow Hund's rule, and it has been proposed that magnetic superatoms can be stabilized by doping simple metal clusters with magnetic atoms. Here, we present evidence of the existence of a magnetic superatom and the determination of its spin moment. Our approach combines first principles studies with negative ion photoelectron experiments and enables a unique identification of the ground state and spin multiplicity. The studies indicate VNa8 to be a magnetic superatom with a filled d-subshell and a magnetic moment of 5.0 mu(B). Its low electron affinity is consistent with filled subshell and enhanced stability. The synthesis of this species opens the pathway to investigate the spin-dependent electronics of the new magnetic motifs.