In addition to being spectacular objects, very massive stars (VMS) are suspected to have a tremendous impact on their environment and on the whole cosmic evolution. The nucleosynthesis both during their advanced stages and their final explosion likely contribute greatly to the overall enrichment of the Universe. Their resulting Supernovae are candidates for the most superluminous events and their extreme conditions lead also to very important radiative and mechanical feedback effects, from local to cosmic scale.

In this thesis, we explore the impact of rotation and metallcity on the evolution of very massive stars across the cosmic time. By implementating an equation of state in the GENEC stellar evolution code (Eggenberger et al. 2008), appropriate for describing the conditions in the central regions of very massive stars in the advanced phases, we present new results on VMS evolution and final fate from Population III to solar metallicity.