Who is Marcus Welby?

This has been driving me crazy for months! Remember in The Wedding Planner when Eddy tells Mary that his mother wanted him to be Fred Astaire, but he wanted to be Marcus Welby? For years I’ve felt like a complete idiot because I had no idea who Marcus Welby was. Well, for those of you who have been living in the dark with me. . .he is a television character from the 1970s. http://www.museum.tv/archives/etv/M/htmlM/marcuswelby/marcuswelby.htm