7. Highlander III: The Final Dimension
Highlander II made such a mess of the series – what with the alien retcon and incomprehensible story – that the next movie had no choice but to ignore it. The Final Dimension (also known as The Sorcerer and The Final Conflict) has Connor forced to fight an enemy from the past; he’s also forced to repeat the exact same plot of the original.
It’s probably the best of the sequels – which is the faintest praise possible – and Christopher Lambert helps inject some life into it. It was far from final, though, with Lambert returning again for Highlander: Endgame a few years later. Endgame merged the continuities of the TV show and the movies together, which had the unfortunate side effect of knocking the third movie out of continuity too.
Lambert had clearly had his fill of high landing by then, so he’s absent from the fifth movie The Source; given how wretched that entry was, it’s hard to blame him.