Established Songwriters who have done entire albums comprised of Cover Songs?

Bryan Ferry also did These Foolish Things and Another Time, Another Place.

Bryan Ferry’s first solo album was all covers. A very fine album, IMHO, with more or less every song as enjoyable on its own merits as the original, and in some cases a distinct improvement. Very classy, full of inventive arrangmeents that make sense, and well worth a listen.

Slayer’s album “Undisputed attitude” is mostly punk covers, with a couple of their own punk songs scattered about.

Firewater (aka Tod Ashley from the late, lamented Cop Shoot Cop + backup band) did an album of covers called Songs We Should Have Written.

Former Marillion singer Fish did a great all-covers album called Songs from the Mirror.

Yes, she’s holding the book on the cover of the record. Er, CD.