Lucille Ball?
Perhaps this was intentional on the part of Ellen, but I noticed in this series that Ellen did a lot of "lone" segments where she would be alone on camera in a room where she would interact with some gadget or something...and would wind up screwing the whole thing up. For example, at the dentist office when she's alone she plays with the tools and blows up that rubber glove....or when she's alone at home and does that skiing exercise bit...or when she tries to put the water bottle on the water cooler herself and winds up spilling it all over the kitchen.
Watching old Lucy episodes over the years, Ellen seemed to really emulate Lucy's style in that way...and did so very effectively. Rarely do I ever laugh out loud at a funny show...I usually just smile. But, Ellen's shows often make me laugh very hard. Her jokes, her antics, the way she can make fun of herself, but not have it be a negative thing. You wind up liking her more.
Ellen truly is a comedic genius, in my opinion and I think that's proven out by the fact that she succeeds in almost any venue (well, except that stinker movie she did). Stand up comedy...brilliant. As a sitcom actor, she was brilliant. As a talk show host...brilliant. Emmy Awards, brilliant. And I'm sure she'll be wonderful at the next Academy Awards.