I kinda think that's a dubious term to begin with (e.g., an act that was a OHW in the US likely was not outside of the US), but even noting that reality, I'll cite a few
Buggles · Video Killed the Radio Star
Modern English · I Melt With You
The Nerves · Hanging on the Telephone (preferred to the Blondie cover)
Big Country · In a Big Country
Red Rockers · China
M · Pop Muzik
Nena · 99 Luftballons
Peter Schilling · Major Tom
Naked Eyes · Always Something There to Remind Me
Aldo Nova · Fantasy
Saga · On the Loose
K's Choice · Not an Addict
cover songs:
Soft Cell · Tainted Love / Where Did Our Love Go?
Flying Lizards · Money
After the Fire · Der Kommissar (though the Falco original is preferable)
It's tempting to include things like Real Life, Thomas Dolby, A-ha, The Outfield, Letters to Cleo, but they had more than one track on mainstream radio / MTV rotation, or more than one good track, and then for example where do you draw the line between, say, Tubeway Army and Gary Numan solo?