Nirvana

The London–based duo of the same name was formed in 1966 as the performing arm of Irish musician Patrick Campbell-Lyons, his Greek songwriting partner Alex Spyropoulos, and English producer Ray Singer. They're best remembered for the 1968 single Rainbow Chaser, which was their only hit – reaching No. 34 on the UK chart. According to Wikipedia they were "acclaimed both by music industry professionals and by critics", despite their "limited commercial success".

The London Nirvana split up in 1971, but reformed in 1985. They subsequently sued Kurt Cobain's outfit, and the matter was settled out of court for a reported $100,000 – both groups continuing to use the name.

The American Nirvana ceased to exist after Cobain's suicide in 1994. According to Wikipedia, their London–based namesakes are still active (in 2023) – although Wikipedia suggests strongly that they've never been able to perform live as they rely on multi'tracking, and it doesn't mention any new material since 1999.