Bands who only do covers

Who are some bands who have only released covers so far? Scandinavian Metal Praise comes to mind. There's also Animetal USA but that's a gray area as they do cover the anime themes, but the lyrics are all new for the most part (and if we're going to count putting new lyrics over existing melodies, then you might as well put Apologetix on the list).

Greta Van Fleet have released nothing but albums of Led Zeppelin covers.

There are quite a few cover bands on You Tube.  Some are awesome, others are trying.  
There's that guy Leo Moracchioli who does metal covers of pop songs.
There are also quite a few jazz bands who do jazzy covers of metal songs.  
And prog rock cover bands who do some really hard-to-duplicate prog classics.  
I do not remember their names but when I come across them, I sometimes check them out.