The Whitey Murphy character was introduced in the 1941 Adventures of Captain Marvel movie serial in which Whitey was a friend of Billy Batsons. Murphy was played by actor William Benedict.
Whitey makes his first appearance in Whiz Comics #22 (published September 5, 1941) in the story "Captain Marvel and the Temple of Itzalotahui." Whitey stops by Billy's office at W.H.I.Z. and the two young men are reunited after working on the Captain Marvel movie together and go on a wonderful adventure!
Even though Whitey Murphy was first introduced to us in the Captain Marvel movie, I'm glad they incorporated him into Cap's comics. He's a great friend of Billy's and a great character who appears now and then on the pages of both the golden-age comics and the Shazam! comics of the 70s.