Last summer, ‘Saturday Night Live’ hired five new cast members to replace the large shoes left by the departures of veterans Bill Hader, Jason Sudeikis and Fred Armisen – plus Tim Robinson, whose quirky style was, after just one season, reassigned to the writing staff. Those five new hires were Beck Bennett, Noël Wells, Brooks Wheelan, Kyle Mooney and John Milhiser. In January, the show added Sasheer Zamata. Then, in February, after the departure of 'SNL's' most tenured cast member, Seth Meyers, co-head writer Colin Jost joined the cast.

So, in a season filled with new faces – and a now whopping 17 cast members – competing for that ever-precious airtime, it’s notable that the new cast member who, at the very least, has had the most artistic impact on the show – and is certainly the boldest cast member this season – was introduced to the world by a nearly asterisked “promoted from the writing staff” designation...a 37-year-old actor/writer/comedian who used to go by the name Pat O’Brien.

After graduating from the University of Michigan in 1999 (where he almost majored in pre-med or engineering), O’Brien – who, today, uses the shortened version of his given first name, Mike – spent the next ten years at Chicago’s improv theater, iO, and at the famed Second City. O’Brien auditioned for ‘SNL’ as early as 2005, but wasn’t added to the writing staff until 2009.

Bill Hader, who worked with O’Brien from 2009 until Hader left the show in 2013, remembers hearing about a talented writer from Chicago named Pat O’Brien, but didn’t quite make the connection when he first met Mike O’Brien, “I met this guy, Mike, so I didn’t know. I was looking for a guy named Pat! The whole time I was like, ‘I guess that Pat guy didn’t make it. That’s too bad. But this Mike guy is really funny.’”

And Hader noticed something that was peculiar about this Mike fellow, especially for a brand spanking new ‘SNL’ writer, “Even from his first pitch meeting as a writer, he was fearless. He would just pitch these insane pitches … he did not give a shit.”

“As a writer,” Hader continues, “you want to stay out of the way and you want to embrace yourself to the cast and the other writers and Seth Meyers, who was the head writer at the time. You want to be a team player. And Mike was that, but he just very much had his own style. I remember I was told when I started at ‘SNL’ – it was good advice – it was like, ‘Here’s what the show finds funny and there’s what you find funny and you have to find the Venn diagram of where they overlay.’ And there were some people in my time there like John Mulaney, Kristin Wiig – what they found funny and what the show found funny was the exact same thing. There was no overlay; it was like a carbon copy. Mike was someone that didn’t give a shit about the Venn diagram.”

In the 2012-2013 season, O’Brien wrote two of the best and most memorable sketches from that season: one was a prerecorded short film titled ‘Sad Mouse,’ which saw host Bruno Mars play a very distraught man who accepts a job as a Times Square costumed mouse, and whose sadness we watch became more and more palpable as he makes his way through a series of disappointing interactions with New York City tourists.

And – co-written by John Solomon and Rob Kline – there was Bill Hader as an Army veteran named Anthony Peter Coleman who joins a puppet class, where the horrors of his time in Grenada are presented through his puppet, “Tony.”

Even from these two sketches – sketches in which O’Brien doesn’t even appear – what makes O’Brien’s humor fascinating is that he can somehow combine funny, weird and sincerity into one discombobulated organism … and somehow it works. We are not repulsed by the weird person on our screen. We want to be the weird person’s friend. It takes a special kind of talent to pull that off. Or, as Hader says of Anthony Peter Coleman, “There was kind of an empathy to that guy. He went through this awful time and he was just trying to work out some shit in the puppet class.”

For his first few years on 'SNL,' O’Brien made infrequent appearances in sketches, most notably as the doorman to the Five Timers Club when Justin Timberlake earned that distinction (a role that Conan O’Brien played when Tom Hanks was bestowed with that honor in 1990). But he was best known for his web series, ‘7 Minutes in Heaven with Mike O’Brien.’ Conceived in 2011 (and backed by Lorne Michaels), O’Brien would interview a person of interest while in a closet and then, yes, try to kiss them at the end of the segment. Here’s O’Brien asking his then-officemate Jason Sudeikis to read the same line three times: once as a father, once as a coach, then as a game show host. (And, yes, at the end they kiss.)

In the summer of 2013, O’Brien was promoted to featured player in the ‘SNL’ cast. It was a quiet start, but something changed in November when Josh Hutcherson hosted: O’Brien stared in a sketch called ‘Bugs’ in which, yes, Mike O’Brien tries to interview actual bugs on the streets on New York City. The bugs, of course, never answer, because they are bugs. It was the type of sketch that announced (to paraphrase Bill Hader), “I don’t give a shit.”

In a season of ‘SNL’ that seems to rely more on current popular culture references than in past seasons (though, less at this point in the season than the beginning), O’Brien’s visual non-sequiturs are even more striking. While the team of Beck Bennett and Kyle Mooney trade mostly on their love of a) ironic “bro” humor and b) the ‘90s with successful results, it’s kind of hard to pinpoint exactly what it is O’Brien gravitates toward … except a really bizarre sense of sincerity.

This bizarre sincerity is best seen in a sketch that aired when Seth Rogen hosted, a strange tale of two monsters who undergo plastic surgery, titled ‘Monster Pals.’ It’s the kind of sketch that somehow makes a viewer laugh and captures our interest enough that we start to actually care about O’Brien’s character.

O’Brien pulled this off again just this past week with ‘Dragon Babies.’ O’Brien plays Rick Shoulders, a retired Chicago police officer who is voicing a role in a new animated feature. Shoulders laments about the two worst days of his life: Losing a voice role in ‘Madagascar’ and the time he shot an unarmed man ten times. This is quintessential Mike O’Brien: What Shoulders is saying is absolutely horrifying, yet he’s played with such sincerity that it’s hard to feel anything but empathy for Shoulders.

It would be easy to compare O’Brien’s work to Will Forte. Both seem to love the strange characters, though where Forte pushed the limit on just how weird a sketch could be – remember, this is the man who, before all of the critical acclaim for ‘Nebraska,’ made a movie in which his character runs around with a stick of celery up his ass – O’Brien pushes those limits, then, when he gets to those limits, turns the ship in the direction of earnestness.

“Will Forte comes from that Groundlings kind of world,” says Hader, “which is always really great characters and amped up to a place that’s unreal, but amazing character stuff. And Mike is such an exemplary Second City type person … Chicago people are very kind of romantic. I always feel they have an idealism or romanticism, which is really nice.”

Though, not every Mike O’Brien sketch is ready for network television. Bill Hader recalls a cut sketch that … well, let’s just let Hader tell the story:

“He did one thing with me that never made it to air, but it was so funny. It was a crazy sketch where it opened up in a living room in a house. And the living room is completely trashed. And there’s a husband and wife staring, exasperated, looking at me. The idea was, I was a vacuum cleaner salesman and I’ve made complete mess of things. And I was giving a presentation and it’s all fucked up. And the whole thing was me going, ‘So, you guys want me to leave, right?’ Like, that’s how it started. Then going, ‘But is there any way possible I could talk you into getting one of our new—Mom, you’re not into this?’ And then the host was always a female host and she runs in and she’s my girlfriend and she’s like, ‘I’m still pregnant!’ And I go, ‘Did you drink the whole thing?’ I mean, it was awful. And then we’d scream at each other. And then the end of the sketch was the opening. The sketch ends with that couple in the living room and the living room is normal and the doorbell rings and she answers it and it’s me, ‘Hi, I’m here to sell you a vacuum cleaner,’ and I step on their cat and I kill it. And I go, ‘Oh no,’ like it got off on the wrong foot.

“And everyone at the table was like, ‘What the fuck was that?’ Like, everyone was laughing so hard, but it was the logic of it. It was a non-linear style. In Mike’s mind, ‘We should we begin this at the absolute funniest place. Fuck building to something, I want to begin this at the funniest moment. Then I’ll go back and show you what happened already.’ And it just went against all sketch logic, but I admired the hell out of it. I was like, ‘God, that was funny and you are just fearless.’ He really is fearless … it’s so disturbing. It’s funny, but it’s really disturbing. The woman is trying to abort her baby, that’s really fucked up.”

And it’s just interesting to listen to a guy like Hader, one of the true greats in ‘SNL’ history, be in awe of O’Brien’s gumption when it comes to what he tries to get on the air.

“The live audience at ‘SNL,’ that’s who’s important,” Hader explains. “More so than the people at home … and especially toward the end at ‘SNL’ I would go, ‘If we did this? Eh, no, they’ll hate that.’ Like, I’ve tried that move before and it fell on its face. And so you try to figure something out that will make them laugh and you laugh and what works on the show – and Mike doesn’t have that. I respect the hell out of him. I was like, ‘I wish I could be brave like Mike O’Brien, who puts up these weird fucking things and does not care.' But things have a real sincerity to them and a real layer to them other than, ‘Hey, look, we’re just fucking off.’”

It’s too early to make any kind of grand declaration about what O’Brien’s legacy at ‘SNL’ will become. It’s doubtful that he’ll become the go-to, most popular cast member on the show (though, I suspect he doesn’t care too much about that). But, it’s certainly not too early to point out that O’Brien is doing stuff on the show right now that is incredibly unique – to a point where I don’t feel it’s hyperbolic to say that, with his talent for combining “strange” and “sincerity,” there’s never been anyone quite like him to ever before pass through the halls of Studio 8H.

And, the thing is, O’Brien’s sincerity doesn’t stop with his sketch work, as Hader remembers the night of a goodbye dinner for O’Brien’s office partner, Jason Sudeikis, “We had a dinner for Jason Sudeikis, this dinner for him when he was leaving the show. The whole cast of ‘SNL’ was at this dinner; it was a surprise dinner for Jason. And Mike gave the most beautiful speech. It was the most wonderful speech for Jason and I was like, ‘Wow, Mike is a real mensch.’”

Mike Ryan is the senior editor of ScreenCrush. You can contact him directly on Twitter.