B'Sides Themselves is a compilation of single B-sides by the British neo-prog band Marillion, which was released on CD only in January 1988. This was the first time that those B-sides were made available in the then still relatively new Compact Disc format. However, vinyl LP and cassette versions were issued in June 1988.

"Market Square Heroes" is the debut single by the British neo-prog band Marillion, released in October 1982 with "Three Boats Down from the Candy" as the B-side. The 12-inch single included an additional track, the 17:15-minute-long "Grendel".