The actor behind Sheldon Cooper, Jim Parsons, has written an emotional letter to the fans and cast of The Big Bang Theory following the announcement that the show would be coming to an end. Set to air its 12th and final season next month, Chuck Lorre and Bill Prady's The Big Bang Theory tells the story of four geeks who gradually learn to interact outside of their own individual comfort zones, largely thanks to the appearance of a waitress/aspiring actress called Penny who befriends the group. The sitcom has become one of the most popular and successful comedy series of all time, picking up numerous Emmy gongs along the way and launching the spinoff series Young Sheldon in 2017.

This week however, it was announced that The Big Bang Theory would be brought to a close, the reason for which reportedly being that actor Parsons was unwilling to renew his contract and that producers felt the show could not continue without the presence of Sheldon Cooper. Several actors have already publicly addressed the news, with Mayim Bialik, who plays Sheldon's wife on the show, expressing her sadness at the decision.

Related: Macaulay Culkin Explains Why He Turned Down Starring In Big Bang Theory

Parsons himself has now spoken out about the end of The Big Bang Theory by posting an emotional letter to both fans and fellow cast members on his Instagram. Alongside a picture of the main cast, Parsons writes:

"It is hard (nearly impossible actually) to really accept that this is a picture of the first of the final 24 episodes we will shoot for The Big Bang Theory. I feel very fortunate that we have another 23 episodes to shoot this season because I am hopeful that with each and every one, my level of REALLY accepting this fact will sink in. Something else I feel grateful for - and this gratitude needs no time to "sink in" or becoming more "realized;" this grateful feeling is always with me but is multiplied in this moment of us announcing our final season - but I feel such intense gratitude for our devoted viewers who are the ACTUAL reason we have been graced with the opportunity to explore these characters for 12 years of our lives.

I feel grateful to our crew - many, many of whom have been with us since day one - and who are the people who bring a sense of steadiness and dependability, who are so warm and kind and always quick to say hello and smile at us every time we come to the set and who, even though you don't see them on TV, are in many ways the real and steady heartbeat that keeps this body of work alive and breathing while we, like flailing arms and legs, act like jackasses and fools in attempt to make someone laugh.

I am grateful to all the writers of the show - those with us now and those that have come and gone - because, without them, there would literally be no Big Bang Theory at all, ever. The writers thought of this show, the writers created these characters, the writers are the ones who found ways to keep coming up with organic, entertaining ways to keep the life of this show going which is a task much, much more challenging than anyone other than them will ever know or understand.

And while I know that they already know it, it bears repeating again and again: I am so terribly grateful for the cast in this picture and the cast members who aren't pictured here - whether they were in one scene or many episodes along the way; you are all my playmates that I have fallen in love with and who have become a part of my life on set and off. You are my playmates when we don't feel like playing but have to because it's our job to get out there and communicate and pretend we're these other fictional people and we look into each other's eyes and say these words and end up creating this weird, other reality that has enriched my life more than I will ever fully understand. I will miss of all you and all of this more than I can say and more than I can know at this time."

The letter certainly covers all bases as far as thanking fans and colleagues goes and given how long Parsons, and indeed many of the cast, have been playing these roles, it's understandable that the end of The Big Bang Theory is taking an emotional toll on those involved. Perhaps unsurprisingly, Parsons doesn't address whether or not it was his decision to leave the show that triggered this situation, nor does he offer any clear reasons as to why he wanted out. His comment regarding the writers having a tough challenge in keeping the show constantly fresh could be a subtle hint, however.

In either case, this move has arguably been on the cards for quite some time. Over recent seasons, there have been numerous reports of contract disputes between the core cast of The Big Bang Theory, with actors supposedly coming close to walking away on several occasions. The Big Bang Theory has also come under increasing scrutiny from viewers and has been frequently criticized for a formulaic approach and a lack of original ideas in later seasons. Some even feel that the show too often relies on stereotypes of geek culture, race or medical conditions such as Asperger's syndrome as the source of its humor.

More: Big Bang Theory Season 12 Will Feature A Direct Young Sheldon Connection

The Big Bang Theory season 12 premieres September 24th on CBS.

Source: Jim Parsons