"Big Bang Theory" star Jim Parsons opened "Saturday Night Live" with a song about how actors — in real life — are nothing like the famous TV characters they portray on-screen.

"People have a hard time separating you from your character," explained Parsons. "I am not like Sheldon. I am not a scientist. I do not speak Klingon. I do have a male roommate, but I assure you it's a vastly different arrangement."

Parsons then broke out into a song titled "I'm Not That Guy," referencing iconic TV characters from the past and the actors who played them.

"In the 90s there was Urkel, he made Friday nights a blast, but Jaleel White — he's a full grown man— who could probably kick your a--."

"Jason Alexander, now and always George Costanza, but did you know he won a Tony because he can sing and dance-a?"

"Henry Winkler as The Fonz, the epitome of cool — but in real life, he was a nice Jewish boy who went to Yale drama school."

"Billy Cosby on 'The Cosby Show,' he had bright sweaters galore. But there's a real Bill Cosby — and he likes sweaters even more."

"Her role on 'Murder She Wrote' was sweet old Jessica Fletcher, but Angela Lansbury, she robbed 50 banks — and nobody could catch her."

Watch Parson's opening monologue in its entirety below:

See Also:

'SNL' Cold Open Parodies Johnny Weir On 'Ellen''American Idol' Will Lose Money For First Time Ever Thanks To Stars' Ridiculous Salaries Here's What The 'Today Show' Hosts Look Like Without Makeup

SEE ALSO: 'SNL' Cold Open Mocks Johnny Weir On 'Ellen'

MORE: 1860s Movie Critic Jebidiah Atkinson Slams Oscars During Colin Jost's 'Weekend Update' Debut