The 'Mad Men' star was made to audition seven times for the show as bosses said he "wasn't sexy enough" but he's now been branded one of the sexiest men alive and he's confessed he can't get his head around the label.
He told Britain's Grazia magazine: "The idea of being a sex symbol is something I don't relate to at all. I find it so confusing and silly."
The 43-year-old actor, who stars as Advertising Director Don Draper in the long-running series, has been in a relationship with actress and screenwriter Jennifer Westfeldt for 17 years but he's admitted they have no plans to get married.
He explained: "I'm not against it; [marriage] marriage works for a lot of people - they call it an institution for a reason."
However, Jon feels it is a decision for each individual couple to make and has no problem with gay marriage.
He added: "I think everyone should be able to get married - or not. Gay, straight, knock yourself out; if that's your jam, do it."