There are many instances of singers from hit making bands leaving to embark on solo careers and having subsequent hits under their own names. There are also a number of bands who have had multiple hits sung by different band members. The category in question here is a bit more rare. These are cases where a lead singer was the voice of at least one noteworthy hit with one act, then resurfaced, sometimes years later, with another group and again sang lead on a memorable chart hit.
It's likely that these are not the only singers to have accomplished this feat, but these are the ones that came to mind. It's noteworthy that there are no female singers here. Frequently when a female vocalist had a few hits fronting a band, they would then be packaged as a solo act and any later hits under their own name wouldn't qualify them for inclusion here.
Free free to comment with names I've missed.