The Big Bang Theory elevated the genre of American sitcom during its unprecedented 12-year run, but for Kaley Cuoco and Johnny Galecki, it was a completely different tale.

The Big Bang Theory has allowed its fans to enjoy a certain amount of hilariously entertaining respite during its 12 years of airing. The network sitcom may have broken all kinds of records, and even established a few in that time, but none shines through more than the wonderful bond between the leads.

In a case of life resembling art, a famous on-screen couple from The Big Bang Theory ended up dating in real life, too. But time and other complexities gradually drove them apart. At the same time, the creator of the show, Chuck Lorre, knew just the right recipe to lift the spirits of his stars to deliver a consistent quality of his show.

The Big Bang Theory established itself in 2007, a year that marked the beginning of a long and fruitful relationship between audiences and the show's socially awkward nerds. But beyond its math and science arc, The Big Bang Theory was known for hosting one of the most epic sitcom pairings on television.