Very massive stars (VMS) are dominant sources of ionising radiation. The prime difference between VMS in our local Universe and those in the Early Universe is their metallicity (Z), which leads to differences in mass loss and evolution, but also to different amounts of ionising flux, black hole masses, and the effective stellar upper-mass limit. HST is observing hundreds of massive stars in the Small and Large Magellanic Clouds (SMC & LMC) under the ULLYSES programme to study the winds and feedback of low-Z stars. Radiation-driven wind theory predicts a strong dependence of their strength on the host galaxy Z, and while initial studies support the predicted mass-loss-Z dependence, ULLYSES and its optical counterpart "X-SHOOTING ULLYSES" are testing this on a large sample for the first time. X-Shooting Ullyses will have massive consequences for our understanding of massive-star formation and evolution, feedback, and gravitational-wave events at low Z, which I place into Cosmological context. Those unable to attend the colloquium in person are invited to participate online through Zoom (Meeting ID: 942 0262 2849, passcode 792771) using the link: https://zoom.us/j/94202622849?pwd=dGlPQXBiUytzY1M2UE5oUDRhbzNOZz09 Prof. Vink will be based at the Astronomisches Rechen-Institut during his visit to Heidelberg, and will be available for meetings by arrangement with his host, Andreas Sander (andreas.sander@uni-heidelberg.de).