  The amount of mass loss is of fundamental importance to the lives and deaths
of very massive stars, the input of chemical elements and momentum into the
interstellar and intergalactic media, as well as the emitted ionizing
radiation. I review mass-loss predictions for hot massive stars as a function
of metal content for groups of OB stars, Luminous Blue Variables, and
Wolf-Rayet stars. Although it is found that the predicted mass-loss rates drop
steeply with decreasing metal content (Mdot ~ Z^{0.7-0.85}), I highlight two
pieces of physics that are often overlooked: (i) mass-loss predictions for
massive stars approaching the Eddington limit, and for (ii) stars that have
enriched their own atmospheres with primary elements such as carbon. Both of
these effects may significantly boost the mass-loss rates of the first stars -
relevant for the reionization of the Universe, and a potential pre-enrichment
of the intergalactic medium - prior to the first supernova explosions.
