Jeff Findley wrote:
How about the ATV? The quick search I did says "The ATV uses up to 4.7
tonnes of propellant to raise the ISS altitude which naturally decreases
with the residual atmospheric drag.". It's also able to "carry 9 tonnes of
scientific equipment, general supplies, water, oxygen and propellant".
What's not clear to me is whether or not it's own engines use the same tanks
which would be used to transfer propellant to (and from?) ISS.

My memory is that ATV can supply propellant to ISS, but it's own
thrusters use N204/MMH, while ISS/Soyuz/Progress use N204/UDMH