ITT: Post bands that produced either exactly one proper full-length album (some singles/EPs are fine, too) or just some singles/EPs. The more obscure, the better.
I don't consider discography compilations (demo collections, complete discographies, et cetera) to be albums, so they're fair to post as long as they haven't released any new album at the time of your posting.
I'll start with some quality NWOBHM.
The late '70s/early '80s was filled with bands who released one or two singles, perhaps an EP or exactly one full-length, and then disappeared. Usually, these bands resurface by releasing their remastered demos.
Here's Y Diawled, the world's first Cymraeg-language band
The band released a couple singles before calling it quits, but despite the off-key singing, the riffage is top-notch.