I will report on our recent discovery of a wide-spread photometric variability among hot (~20,000 – 30,000 K) extreme horizontal branch (EHB) stars in Galactic globular clusters. The EHB variability is periodic, displaying single-wave, low-amplitude and ~2-50 days modulations. The variability cannot be ascribed to either binary evolution or pulsation and it is attributed to the presence of magnetic spots: superficial chemical inhomogeneities whose projected rotation induces the variability. We conclude that weak magnetism (<= 400 G) is a key player driving the formation and evolution of EHB clusters stars and, likewise, operating in the Galactic field sdB counterparts. Furthermore, our results suggest similar variability/magnetism phenomena in all radiative-enveloped (MS/WD) hot-stars, in the same temperature regime.