Lionel Haemmerle - March 22, 2018 Life and Death of Supermassive Stars The recent discovery of quasars at high redshifts, powered by supermassive black holes, challenges our understanding of the early Universe. A promising pathway for their formation is the direct collapse scenario, in which an atomically cooled halo of about 10^7 Msun collapses without fragmentation. A stellar object forms and becomes supermassive (M>10^4 Msun) by accretion at rates 1-10 Msun/yr, before collapsing to a black hole through the general relativistic instability. However, the consistency of this scenario depends on the properties of supermassive stars, because the radiative feedback and the angular momentum barrier could disrupt the accretion process and limit the growth of the remnant black hole. In order to address this issue, I present new numerical models of supermassive stars that include accretion and rotation.