The comedian, whose FX show "Louie," is a consistent critical favorite, used his monologue time to address several topics slightly edgier than the usual "SNL" monologue fare, including racism and the Middle East conflict.
But when he closed out the bit with a routine on child molesters, the audience got audibly uncomfortable.
"How do you think I feel, it's my last show probably," C.K. responded when the audience groaned at one of his molestation jokes.
While there was some definite outrage about the routine on social media, C.K. also had his prominent defenders, including Sean Lennon, who tweeted, "Being too touchy and sensitive about what constitutes funny can actually perpetuate that which offends you in the first place."
Others weren't as amused, including Kings College theology professor Anthony Bradley, who tweeted, "Sorry. Joking about child molestation is bad form. Very low moment for #LouisCK. 100% not funny in any form. 1 in 3 girls, 1 in 6 boys."
You can watch the comedian's entire monologue here.