The program originally premiered on ITV in the U.K., and will air on PBS in the U.S. The show was renewed for a second season in August 2013.
McKellen stars as Freddie Thornhill, an aging actor who lives with his partner of 50 years, Stuart Bixby (Derek Jacobi). The 75-year-old star spoke to Entertainment Weekly about the series, and promoted the show as a "little bit radical."
"Over the years, Derek and I have seen each other and kept in touch," he begins. "We came together very easily. Derek likes a laugh as much as I do, and of course he's an extremely accomplished comedian."
"Their mode of communication is to sound perfectly horribly to each other, hence the title Vicious," he continues. "As with many couples who've fallen into the habit of being rude to each other, I think they love each other -- they certainly still share a bed ... Probably the most remarkable thing about them is not that they're gay, but that they've been together for 50 years."
The actor acknowledges some "don't take to [the show] at all," but says he was attracted to the role "simply by the fun that could be had for the performers and for the audience." He calls the program "radical" in that it "just takes for granted that an audience will find a couple this age who are also gay to be worthy of their own sitcom as any other couple might be."
"Certainly, you can't compare these two to other characters in the past," he asserts. "These two are very at ease with [being gay], and you laugh with them rather than mock them because they're gay. Their gayness is just taken for granted. In a sense, that's rather modern and unusual and very welcome, I think."
Vicious airs Sundays on PBS. McKellen will next appear in The Hobbit: The Battle of the Five Armies on December 17.