One warm, dreamy and magical evening in early 60's Los Angeles, Brian Wilson (musician, singer, songwriter, and record producer who co-founded the Beach Boys) was driving around listening to the car radio. Upon hearing Ronnie Spector and the Wrecking Crew perform Be My Baby, Brian became enraptured, pulled over and underwent a musical epiphany. He set about producing Don't Worry Baby as a response, with Ronnie in mind as the lead singer. Alas, Ronnie was locked inside Phil's castle, agonized, and unavailable to perform anything. Many years later, she did perform Don't Worry Baby.
Here are both recordings.