First recorded (as “Beck”) by Chelsea (c. 1971).
Hit version by KISS (US #7 1977).
From the wiki: “‘Beth’ was co-written (as ‘Beck’) by drummer Peter Criss and guitarist Stan Penridge in 1971 before Criss had joined KISS, while he and Penridge were members of the band Chelsea. (‘Beck’ was the nickname of fellow Chelsea member Mike Brand’s wife, Becky, who would call often during practices to ask Mike when he was coming home.) ‘Beck’ was first recorded sometime around 1971 by Chelsea but now appears only as a bootleg.
“In its next incarnation, the song became a last-minute addition to the 1977 album, Destroyer, released in 1977. According to Bill Aucoin, the manager of KISS at that time, Gene Simmons and Paul Stanley did not want ‘Beth’ on the album because it was not a typical KISS song. Aucoin insisted on keeping the song on the record. During the recording sessions for the song, Criss was the only KISS member in the studio, making it the only group song that features no instrumental performances by any other member of the band. Criss is backed by a piano and a string orchestra, a stark departure from the hard rock-oriented band.
“‘Beth’ was first released as the B-side to ‘Detroit Rock City’ but radio stations, particularly one in Atlanta, Georgia, began playing it more than the A-side and the B-side, ‘Beth’, quickly became a highly-requested selection. Kiss and Casablanca Records then reissued ‘Beth’ as the A-side with ‘Detroit Rock City’ as the B-side. The single went Gold in the United States (the first KISS single to do so) in January 1977. Both producer Bob Ezrin and band member Simmons were also credited with changing the song’s title to ‘Beth’ when recorded by KISS.”
Kiss, “Beth” (1977):