  Mrk 71 is a low metallicity (Z = 0.16 Z_sun) starburst region in the local
dwarf galaxy NGC 2366, hosting two super star clusters (SSCs A and B), and is
recognized as a Green Pea (GP) analog with SSC A responsible for the GP
properties. We present STIS and FOS far-ultraviolet (FUV) spectra of the
embedded SSC Mrk 71-A obtained with the Hubble Space Telescope (HST). The STIS
FUV spectrum shows the characteristic features of very massive stars (VMS,
masses > 100 M_sun) and we derive an age of 1+/-1 Myr by comparison with the
Charlot & Bruzual suite of spectral population synthesis models with upper mass
limits of 300 and 600 M_sun. We compare the STIS spectrum with all known SSC
spectra exhibiting VMS signatures: NGC 5253-5, R136a, NGC 3125-A1 and the z =
2.37 Sunburst cluster. We find that the cluster mass-loss rates and wind
velocities, as characterized by the C IV P Cygni profiles and the He II
emission line strengths, are very similar over Z = 0.16 to 0.4 Z_sun. This
agrees with predictions that the optically thick winds of VMS will be enhanced
near the Eddington limit and show little metallicity dependence. We find very
strong damped Lyman-alpha absorption with log N(H I) = 22.2 cm-2 associated
with Mrk 71-A. We discuss the natal environment of this young SSC in terms of
radiatively-driven winds, catastrophic cooling and recent models where the
cluster is surrounded by highly pressurized clouds with large neutral columns.
