two-hit wonder

gutless wonder

One who lacks guts or courage; a coward.

nine-day wonder

Something that generates interest for a limited time and is then abandoned.

no-hit wonder

A recording artist who proves to be commercially successful, or maintains a long career, without having any hit songs at all.

one-hit wonder

A recording artist known for only one hit song, especially after failing at subsequent attempts at success.

small wonder

An event or fact whose cause or rationale is not difficult to discern; an unsurprising occurrence.