I suspect these are two of the most spectacular ones, albeit before my time:
I'd have thought that anyone who, rather than focusing on nationality, reflected on the playing prospects of the 'keeper we signed from St Helens Town in 1949 might not have thought he'd be quite the success he subsequently proved.
I don't think that many would have expected much, either, from a full-back signed when in his thirties who'd never played in the top flight and had spent most of his career in non-league - certainly not skippering us to a full set of domestic trophies and a European one, racking up almost 250 league appearances in the process.
As for one from my time, maybe someone like Neil McNab - shown the door by Brighton and bought on the cheap because we were desperate. I don't think I ever thought he'd be with us for over six years and a regular for nearly all of that time.