Grin may refer to multiple artists.
1) An early 70s American rock band best-known for featuring Nils Lofgren on guitar;
2) An independent alternative rock band based in Chicago, now known as Quasar Wut-Wut. 1) Grin was an early 70s rock group based in the Washington D.C metro area whose debut release came out in 1971 on the CBS/Spindizzy Label. The group featured a 19-year-old prodigal alumni of Walter Johnson High School in Bethesda, MD, that being Nils Lofgren on guitar.