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| Series | Episodes | Original Run (US) | Key Storylines | |--------|----------|-------------------|----------------| | | 17 | Sept 2007 – May 2008 | Introduction of Leonard, Sheldon, Penny. The “roommate agreement.” Sheldon’s spot on the couch. | | 2 | 23 | Sept 2008 – May 2009 | Introduction of Leslie Winkle (recurring). Leonard & Penny’s first kiss. Sheldon’s rival Barry Kripke. | | 3 | 23 | Sept 2009 – May 2010 | Howard & Bernadette meet. Sheldon & Leonard’s “truce.” Penny cuts her hair (major fan reaction). | | 4 | 24 | Sept 2010 – May 2011 | Amy Farrah Fowler and Bernadette become regulars. Priya (Leonard’s sister) arrives. | | 5 | 24 | Sept 2011 – May 2012 | Howard goes to space. Leonard & Penny break up again. Sheldon & Amy’s first date. | | 6 | 24 | Sept 2012 – May 2013 | Howard returns from space. Raj’s selective mutism improves. Penny gets a real job (sales at Bernadette’s company). | | 7 | 24 | Sept 2013 – May 2014 | Sheldon breaks Amy’s heart. Leonard goes on North Sea expedition. Howard’s mother (voiced by Carol Ann Susi) dies off-screen. | | 8 | 24 | Sept 2014 – May 2015 | Sheldon and Leonard’s friendship fractures over a failed experiment. Penny & Leonard marry in Las Vegas. | | 9 | 24 | Sept 2015 – May 2016 | Sheldon & Amy reunite. Howard & Bernadette’s first child (Halley). Raj dates Emily. | | 10 | 24 | Sept 2016 – May 2017 | Sheldon proposes to Amy. Howard’s second child (Neil Michael). Leonard’s father appears. | | 11 | 24 | Sept 2017 – May 2018 | Sheldon & Amy’s wedding. Introduction of Sheldon’s brother (Jerry O’Connell). | | 12 | 24 | Sept 2018 – May 2019 | Sheldon & Amy win the Nobel Prize. The elevator is fixed (series finale). |
However, a comprehensive guide requires nuance: episode counts, special classifications (e.g., "season zero"), the spin-off ( Young Sheldon ), and why the show ended after 12 series despite record-breaking ratings. Here is every series (season) of The Big Bang Theory , including episode counts, original air dates, and notable plot arcs. how many series of the big bang theory are there
If you’re asking about (the term used outside North America for a full season’s worth of episodes), the direct answer is: | Series | Episodes | Original Run (US)
No. All countries aired 12 seasons. However, some countries (e.g., Japan, Germany) split a single US season into two shorter “series” for broadcast. But on streaming and DVD, it’s always 12. Final Summary | Question | Answer | |----------|--------| | How many series of The Big Bang Theory ? | 12 | | Total episodes | 279 | | Last series aired | 2019 | | Spin-offs (canon) | Young Sheldon (7 series), Georgie & Mandy (ongoing) | | Will there be more? | No (main show ended permanently) | Leonard & Penny’s first kiss
As of 2026, no. Jim Parsons has repeatedly stated he won’t return as Sheldon full-time. He did reprise the role for a voice cameo in Young Sheldon finale.