Password Generator: please add a fifth checkbox to include the entire printable UTF-8 character set, and a slider to tweak how much of the password should use those characters.

The slider is important, because the existing 4 only use a minuscule subset of UTF-8. Without the percentage slider, the password would be utterly dominated by the much larger address space, and any one random password would be unlikely to contain a number or English character.

You could go even further by having a stepwise intermediate: all possible Latin characters. Again with a percentage slider. But this alone would be much simpler to implement, and may be sufficient for most complexity situations where length is artificially constrained by the third party.