  Accurate determination of mass-loss rates from massive stars is important to
understanding stellar and galactic evolution and enrichment of the interstellar
medium. Large-scale structure and variability in stellar winds have significant
effects on mass-loss rates. Time-series observations provide direct
quantification of such variability. Observations of this nature are available
for some Galactic early supergiant stars but not yet for stars in lower
metallicity environments such as the Magellanic Clouds. We utilise ultraviolet
spectra from the Hubble Space Telescope ULLYSES program to demonstrate that the
presence of structure in stellar winds of supergiant stars at low metallicities
may be discerned from single-epoch spectra. We find evidence that, for given
stellar luminosities and mean stellar wind optical depths, structure is more
prevalent at higher metallicities. We confirm, at Large Magellanic Cloud (0.5
Z_solar), Small Magellanic Cloud (0.2 Z_solar) and lower (0.14 -- 0.1 Z_solar)
metallicities, earlier Galactic results that there does not appear to be
correlation between the degree of structure in stellar winds of massive stars
and stellar effective temperature. Similar lack of correlation is found with
regard to terminal velocity of stellar winds. Additional and revised values for
radial velocities of stars and terminal velocities of stellar winds are
presented. Direct evidence of temporal variability, on timescales of several
days, in stellar wind at low metallicity is found. We illustrate that narrow
absorption components in wind-formed profiles of Galactic OB stellar spectra
remain common in early B supergiant spectra at low metallicities, providing
means for better constraining hot, massive star mass-loss rates.
