Thespian Andrew Rannells is well-known for originating the role of Elder Price in “The Book of Mormon” on Broadway, as well as appearing as Elijah on HBO’s “Girls.” Now the multi-talented performer not only lends his voice to Netflix’s animated comedy “Big Mouth” and stars opposite Don Cheadle in Showtime’s Wall Street comedy “Black Monday,” but he also authored a memoir entitled “Too Much is Not Enough.”

What made you connect with your character of Blair in “Black Monday”?

Co-creators David [Caspe] and Jordan [Cahan] sat me down and told me their vision for the whole season, and the arc reminded me a lot of what my character, Elder Price, went through in “The Book of Mormon,” actually. And also very similar to me moving to New York from Nebraska, with no contacts and having to start my career from scratch. That’s a lot of what Blair is doing in “Black Monday.” He doesn’t really know anybody, he falls into this group of ragtag traders on Wall Street that are very much outsiders, and he creates this life and career. He starts off very optimistic and would like to think that business is fair and you work hard and then you’re rewarded for it, but he very quickly learns that that’s not how the world works, unfortunately, always. So he has to change his viewpoint and change his plan in order to catch up with these guys and try to become successful in this world where not everybody is that audience. I really liked that aspect and that, probably of all of the characters, goes through the biggest change. I thought it would be really fun as an actor to play somebody who’s reinventing himself over the course of a show.

Do you feel that, as time goes on, he’s changing into someone else, or revealing truer parts of himself?

I think that’s more the case. He’s obviously somebody who’s very ambitious and for anyone who has an ambition like that, there’s a hunger in there that I think might be sometimes covered by politeness, but I think he learns there’s just not a place for that. I think he was always ambitious, and he’s coming into his own, for better and for worse.

Which of his on-screen relationships most helped you understand who he is and who he was becoming?

I learned on Casey Wilson a lot in not only figuring out who he is professionally but also who he is personally. But I would say the relationship that was ultimately the most informative was the one Blair makes with Dawn, who is Regina Hall’s character. That was the thing that became the most helpful because that’s the only person that he’s really honest with. He sort of confesses to her his transformation that he’s going through and the realizations he’s having about himself and his work and how he wants to live. That’s the only person he’s 100% honest with.

How playful were you able to be in such character and relationship-heavy scenes?

The character was very well-drawn out, I have to say, so a lot of the information was there on the page for me. I guess I would say the thing that I added was a slightly darker side to people who seem nice and friendly — but there’s an undercurrent of ambition and some anger and some feelings of insecurity and wanting more but maybe not exactly sure how to get it just yet. … Oddly, it came out in scenes with Casey Wilson in the third episode where I go out with Don [Cheadle’s character], and I try cocaine for the first time, and it just sort of unleashes this monster inside of him. Casey and I were able to improvise much of the argument [that comes after]. They just let us have this very outrageous argument that I think really colored who actually these people are. That was really fun, and I was really grateful that Jordan and David allowed us to have that space because improvising can be fun, but it doesn’t always necessarily serve the story. But if you are able to stumble upon something organically that is informative, then it’s amazing.

To what do you attribute that willingness from them to be collaborative?

I think they trusted us. Don, Regina and I were not going to hijack every scene with things we thought were funny. I can tell you from improvising a lot on “Girls” that sometimes it’s really great but sometimes it does take you off-track a little bit and then you have to work your way back in. But I think Jordan and David really trusted us, and I trusted them. I knew they weren’t going to let us go too far — I knew there was always going to be a reason for what we were doing and a reason why we were telling the story in this particular way or at this pace or with these particular lines. So when everybody trusts each other like that, it makes it easier to do your job.

In addition to “Black Monday,” you are also one of the stars of “Big Mouth.” How differently do you approach voice-over work?

I will say that first season of “Big Mouth” where we didn’t really know what anything was going to end up looking like, it was kind of a big question mark. So the second season, and now we just finished our third season, that became much easier because you could picture what that guy looks like and what his mannerisms are. But that said, there is a lot of freedom to just create something from scratch and then have the animators draw in the attitude you’ve given them. It’s a very different creative process but one I’ve always loved doing.

What does voice-over work fulfill for you that is different from live-action?

You don’t have any physical boundaries, so you can do anything. It’s very creative, in that sense, because you don’t have to keep yourself in the realm of reality. I imagine it’s like doing some sort of big sci-fi where if you’re in front of a green screen — you can make anything happen.

Shows such as “Big Mouth” and “Black Monday” are diving into big issues surrounding coming-of-age and corruption of power, respectively. Is being topical a conscious choice in the shows you join?

Ideally. I’ve been very fortunate, in the projects that I’ve gotten to be a part of, I feel, did have something to say. With “Black Monday,” what my character goes through and what Don’s character goes through is that power is very corrupt, and as you get more of it, people can start to be real a–holes. With Blair it’s a slow burn, and he doesn’t realize exactly how dark things are getting for him because it doesn’t happen over night — it’s a process that he’s going through. And I think that’s it about people in positions of power, they don’t always realize how far they’ve fallen. So stories like this I think are interesting because you can draw them out and shine a light on people who are very human but have lost their way.

How timely, in a specific political sense, are you interested in being with your roles?

I think the interesting thing about doing something that takes place in 1987 is you just realize how cyclical everything is — the financial market, politics. Everything’s constantly changing, but it’s the same pattern of you have a lot of time in a very conservative world, and then there’s the backlash that makes things more liberal and accepting — and then there’s a backlash because of that and we go back to the conservative side. And that’s been happening since the world began. So it’s comforting in some ways, as much as politically speaking in the last couple of years it’s been shocking to see what’s been going on. But then the Vietnam documentary that Ken Burns did for PBS, I found it — comforting is not the right word, but when you realize that living in that moment, living through that time period, I asked my mother after I watched it, “What did that feel like, starting a family after all of that was going on?” And she said it was really terrifying, but then you get through it. She had a family to raise and things to do, and as much as she was focused on it, there was the practical aspects that she had to keep these kids alive. She had a larger picture. So I did find that kind of comforting because if we as a country got through that, then whatever is happening right now is not the end. The world is not going to end because of this one man who is president. Somehow history will right itself and we’ll get back on-track, for a little while at least.

All that being said, what made this the right time for you to also write a book?

I started to write it as just a series of essays that I was writing, just as an exercise. And it was something I had always done, but I never shared them [before]. But I shared them with a friend, and he picked one and sent it to the [New York] Times, and it was published last summer. And I guess when I saw the reaction to that, and now I had this armful of essays that I had already written, it seemed like something I could do — “OK I think I can actually see this project through.” And also, I turned 40 and, looking back to those first years in New York, all of a sudden I was like, “Oh I have a much different perspective now.” I hadn’t really allowed myself to go through things that happened to me at that time, but it seemed like I actually had something to say about that now.

I will also say that working on Broadway a lot, we have a very enthusiastic fanbase of young people, and those kids — a lot of them at the stage door want to be actors, want to be on Broadway in some capacity — will ask a lot about [advice]. They rarely use the word “shortcut,” but that’s implied. Like, “what’s the fastest way I can do this?” But the reality was, there wasn’t for me — there was no fast way. I was in New York for seven years before I got my first Broadway show. So I chose to focus on a time in my life that’s not stories about “The Book of Mormon” or Lena Dunham or television; it’s about all of the stuff that happened before, that got me there. Because I think if you had told me at 19 that it was going to be seven years before I got there, I think I might have been like, “No, maybe I’ll go to law school.” So I wanted to share that particular time to show that it all counts and it all matters, even though it wasn’t maybe as splashy or as shiny as what I get to do now. All of those years were important and not to be discredited. It was all so informative.

What was the balance you wanted to strike between stories of your professional and personal life in the book?

I sort of go for it. I talk about all the things people talk about in memoirs: losing my virginity, when my father died, when my grandmother died. There was a lot of territory that, if I was going to talk about that time period, I had to talk about those things. And I wanted to do it. If you’re doing it, then you should really do it. I didn’t want to soft-pedal anything or graze over anything. I just felt like I needed to be as honest as possible.

Do you have a piece of go-to advice for those you mentioned kids who may be looking for shortcuts to success?

What I came to realize was that I could really only be myself. I spent a lot of time in my early career trying to be what I thought people wanted from me, or what I thought was going to be an effective way to work and live, and that applies to personal relationships as well as my professional life: I spent most of my 20s trying to be something else. And when I accepted the fact that this is my skill set, it’s never going to be right for everything but hopefully it will be right for some things, that’s really when I felt the freedom to just do what I do. And luckily work came that supported that choice. But it took me awhile to get [there], and I think that’s very common for a lot of actors [because] you’re always thinking, “Well, what are they looking for? What does the casting director want?” But as soon as you start saying, “Well, this is what I’ve got, so if you like it I’m available,” if it’s not, that’s OK, too. It’s a hard lesson to learn, so I guess that would be the one piece of advice, but it’s easier said than done, obviously.

When it comes to charities or political causes, what is on the forefront of your mind these days?

I’m a huge supporter of the Trevor Project, and I feel that that is still very much an organization and an issue that we do still need to deal with. I think there’s a misconception that homosexuality is widely accepted now, and why would anybody have a hard time coming out because “Will & Grace” is still popular and everybody’s cool with it now, right? That’s not the case. Coming out can be — even though my family was wildly supportive — it still can be hard and feel very lonely and can be isolating. So that’s not a fight that is completely over just yet. So organizations like that are important. The Trevor Project is really great because they do provide resources to young people who are feeling alone or anxious, and unfortunately that’s always going to be a service that’s needed. Coming-of-age is always going to be something everyone has to go through, so I think it’s great when there are those services in place that can provide help.