Some Fun? "B" Groups/Performers??

Well, I'm not thinking of the Cubs or '70's Iowa or Northwestern,...no, I'm thinking more Dave Clark Five, Del Shannon, Lovin Spoonfull...etc. So, who are you favorite groups or individuals that were never quite #1 or always in the shadows of others. Maybe Dinah Washington or Sarah Vaughn always living down from Billie and Ella... A thought that brought this on..a friend and I were talking of good concerts..and I thought of the time I saw Steve Martin and John Sebastian was his opener.. Well, after the 3rd curtian call Mr Sebastian finally was allowed to leave the stage,..and Steve Martin came out and said..."Did you like John Sebastian"?..and of course the crowd exploded..and Steve said.."last time I'll ever have that a_ _ hole" open.
So, who are your favorite also-rans?