As Big Bang Theory fans know well, sooner or later our favorite TV show comes to an end. The CBS series made it through a full 12 seasons, but we still have to wonder why in the world the series ended. Now we finally know why it got canceled.

Though it went on to have a successful run of 12 seasons, The Big Bang Theory almost didn't get picked up by a network. The Hollywood Reporter reported that Steve Holland, showrunner for a time during the production of the hit TV series, stated that the show's producers didn't really think it would amount to anything even close to what it turned out to be.

In fact, this beloved series almost didn't even include the stunning Kaley Cuoco, who played Penny, the nearby neighbor to Leonard and Sheldon. CBS originally planned to bring in actress Amanda Walsh to play Penny rather than Cuoco. It's a little hard to imagine the show without the vivacity that Cuoco brought to her portrayal of Penny, isn't it?

It's impossible to know whether Walsh would have brought as much chemistry to the set as Cuoco did, but luckily CBS ultimately chose to produce the series after it was reworked and had Cuoco in the cast.

Keep watching to see We Finally Know Why The Big Bang Theory Got Canceled.

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It almost didn't happen | 0:00

There were hints of the end | 1:05

Parsons' exit ended it | 2:00

Parsons had an epiphany | 2:51

The filming style became outdated | 3:35

The ratings were dropping | 04:34

The beginning of the end | 5:28

With age comes... creepiness? | 6:26

The stars weren't surprised | 7:15

Were their salaries a factor? | 8:05

But it was almost renewed | 9:15

Don't hold out for a reunion | 10:07