Mr. Blue"

is a popular song first recorded by DeWayne Blackwell in 1959. It
became a hit for The Fleetwoods, reaching number one on the
Billboard Hot 100 in November 1959 and giving the group its second
chart-topping hit of the year.
The Fleetwoods were a singing trio from Olympia, Washington,  
formed in the late 1950s. They were responsible for eleven hit songs,
beginning with "Come Softly to Me". The song was originally called
"Come Softly", as written and arranged by founding lead singer
Gretchen Christopher.  The group was originally named Two Girls
and a Guy. Gary Troxel and Gretchen Christopher were two Olympia
High School students,waiting for Christopher's mother to pick her up
after school.  Troxel started humming and said it was a jazz trumpet
riff he had in his head. Christopher recognized that it was based on
the same chord progression as the song she had been writing. She
arranged and sang her melody and lyrics in counterpoint to his
background, and liked it enough to ask Troxel to repeat it with her for
Christopher's friend and singing partner, Barbara Ellis.
 The Fleetwoods continued to record into the 1960s, with a number
of other successes. Their second hit, "Graduation's Here"  was
followed by "Mr. Blue," which, like "Come Softly", also topped the pop
charts.