We analyze the spectrum of additive finite-rank deformations of N N Wigner matrices H . The spectrum of the deformed matrix undergoes a transition, associated with the creation or annihilation of an outlier, when an eigenvalue d i of the deformation crosses a critical value˙1. This transition happens on the scale jd i j 1 N 1=3 . We allow the eigenvalues d i of the deformation to depend on N under the condition jjd i j 1j > .log N / C log log N N 1=3 . We make no assumptions on the eigenvectors of the deformation. In the limit N ! 1, we identify the law of the outliers and prove that the nonoutliers close to the spectral edge have a universal distribution coinciding with that of the extremal eigenvalues of a Gaussian matrix ensemble.A key ingredient in our proof is the isotropic local semicircle law, which establishes optimal high-probability bounds on hv ; ..H ´/ 1 m.´/1/wi, where m.´/ is the Stieltjes transform of Wigner's semicircle law and v; w are arbitrary deterministic vectors.