Woah! I made a mistake memory wise. Actor Barry Nelson was the first to play James Bond on TV. As for John Gavin, here’s this:
https://en.wikipedia.org/wiki/John_Gavin
James Bond
Gavin was signed for the role of James Bond in the film Diamonds Are Forever (1971) after George Lazenby left the role.[25] However, David Picker, head of United Artists, wanted the box-office assurance of Sean Connery. Gavin’s contract was honored despite losing the role to Connery. According to Roger Moore’s James Bond Diary, Gavin was slated to play Bond in Live and Let Die (1973), but Harry Saltzman insisted on a British actor for the role and Moore was given the part.[26]
Thanks again for the Wikipedia link. I do remember now that story about him missing out of the James Bond films. I had also forgotten about the movie A Time to Live and a Time to Die. Loved that one too.