Shonda Rhimes, force behind ABC Thursday nights, making television history

NEW YORK (WABC) -- #TGIT, 'Thank Goodness it's Thursday', is a hashtag Shonda Rhimes fans know all too well.

That's because Thursday nights are her night.

With three prime time shows on ABC, Grey's Anatomy, Scandal, and How To Get Away With Murder, it's TV's hottest night.

But besides the ratings success, her shows are known for their diverse casts.

Ask Shonda Rhimes about her impact on prime time and she'll tell you she's just trying to tell great stories, and given the ratings for her three shows, that mission is being accomplished week after week.

But she is also earning her own, unique place in TV history, with the past as prelude.

30 years ago, Bill Cosby changed the face of television.

"People remember the Cosby Show because it was an African American family, but if you recall they always in terms of the people they had over: they had white neighbors. They had Hispanic neighbors. It was a diverse community," said author Mark Whitaker.

A community which celebrated a common humanity.

"An America where people could kind of interact from all kinds of backgrounds," said Whitaker.

He is the author of a definitive new biography of Cosby, and especially well-qualified to talk about his impact, which, he says, had its limits.

"I think it's a source of frustration to Bill Cosby that the impact of The Cosby Show wasn't more long lasting," said Whitaker.

Decades would pass until one of his biggest dreams became a reality.

"In the way that I think Cosby very deliberately said: 'Look just because we're black - doesn't mean we have to be talking about the fact we're black all the time.'"

That simple goal may now be achievable, thanks to the talents of one woman.

"Even though she's not a performer. She's not on-camera, I think the true heir in modern television to Bill Cosby is Shonda Rhimes."

But the lady herself doesn't see it that way.

"I don't know that I've played a role in the greater diversity of prime time in our network or anybody. I've just been telling the stories I've been telling, and there are a lot of talented writers that are getting a lot of good work from that," said Rhimes.

The real truth may be as complex as the characters she creates.

"She has accepted me exactly the way I am and is absolutely open to incorporating who I am into the character," said actress Viola Davis.

Viola Davis, who plays Analise Keating on How To Get Away With Murder, gets the last word for now. What will it say alongside the name of Shonda Rhimes in the history of TV? Hard to say exactly because she's still giving us exciting new chapters every Thursday night.