Joel McHale isn’t lowering anyone’s expectations for The X-Files’ season finale. “It’s going to be the greatest of all time,” McHale told EW.

McHale, who counts himself a “huge” fan of the sci-fi series, returns in Monday’s finale as Tad O’Malley, the conservative Internet talk show host whose conspiracy theories had a hand in bringing Mulder (David Duchovny) and Scully (Gillian Anderson) back to the FBI. In anticipation of the finale, EW caught up with McHale to find out what else O’Malley has in store, why he thinks The X-Files has endured, and how Community prepared him for the part.

ENTERTAINMENT WEEKLY: What can you tease about the finale?
JOEL McHALE: I finally become the main character that I always thought I would be. It’s The Tad O’Malley Files after this. I think everyone wants that. Everyone’s been demanding that … I will say this: All hell is breaking loose. There have been a lot of promises made over the last few episodes, and this will not disappoint.

When Tad romanced Scully in the premiere, were you worried that fans would have it out for you?
If my biggest problem is fans of a very popular, beloved TV show are upset with me because I’m making a move on one of the major characters, then I am the luckiest man alive.

Why do you think The X-Files still appeals to so many people?
I think what Chris Carter did was a very rare thing. It was the combination of many things that television producers and writers have tried forever to make happen: incredibly good writing, an incredibly good idea, original idea, incredibly good chemistry between the main characters. It just doesn’t happen that often. I mean, essentially Chris wrote a procedural science-fiction crime drama — essentially — but you cared deeply about Scully and Mulder, which doesn’t happen very much on procedural crime drama. And on top of that, there are numerous hilarious episodes — truly funny — and that rarely happens. He just kind of invented something that hadn’t been done, and no one has duplicated. No one’s gone 212 episodes.

I think why people come back is because the mythology, the super-story of what’s going on with aliens and conspiracy theories and all that — people are all still very curious about, and they care very deeply about the characters, and they want to know what’s going on with them. I mean, when that first episode aired and 50 million people watched, it was no joke… But that’s my explanation for it. David Duchovny and Gillian Anderson did something that is very difficult to do, which is have great chemistry on screen for that long, and great history. I couldn’t believe — I can’t believe I’m a part of it.

How was the experience on set?
Terrific. I’ve been on a few sets where things are poison. It starts at the top, and crew turns over because they are fed up. It’s not a very happy place. But if you look at Chris Carter’s crew, they all were there from the ‘90s, and they are very devoted to Chris. They love him. On top of that, David Duchovny and Gillian are delights on set. So if you get the most powerful people on set happy, and they’re happy, then the whole place — people want to work.  

Did you try to play it cool about what a fan you are?
Yes. I didn’t want to get on there wearing, you know, like an X-Files sweatshirt with an alien head. I did ask David a very specific question about some episode, and he just kind of looked at me and went like, “Oh. You a fan?” Like I had been sussed out. I’m like, “Yes, I am. What are you going to do about it?” I was more concerned — I mean, yes, there’s the initial, “Holy crap I’m going to be on The X-Files,” but then the next thought was when I got the script, and I’m like, “Holy sh–, this is a lot of dialogue.” Some of it could be on prompter and some of it couldn’t. It was busy.

Chris Carter doesn’t play around with his monologues.
No, he’s not messing around. I thankfully had enough practice as Jeff Winger on Community — he had some pretty epic speeches, so that worked out great. So I have Dan Harmon to thank for that.

Coming back to film the finale, was there a different energy on set than when you were filming the premiere?
No, it was the same. People were having a good time. People were happy to be working on it, because they knew how cool the show was. David and Gillian seemed to be having a really good time, and I was having a good time, and it wasn’t that long of a period of time [that the show was filming]. It was pretty quick … But believe me, if they were to do more, I would show up even if I wasn’t cast. I’d just be like, “I’m here, I’m available.”

So there’s a chance if The X-Files comes back that we might see Tad again?
I don’t know. I would like to. I mean, my character gets killed badly in this episode so maybe not. No, I’m not going to say if I get killed. But if they do more episodes, I’d be there in a New York minute if they want me.

As a fan, what would you want to see from the show in the future?
For that answer, I usually give what I would say about Dan Harmon when they’d be like, “What’s going to happen with Community?” And I’d be like, a.) I don’t know, b.) I’m not funny or smart enough to know or even guess. And that’s why Chris Carter is a genius and I’m not. I could make up all sorts of stuff, but it would be really off and wrong and sad.