Toy Story's plastic dino Rex may have tiny arms, but the role has had a lot of reach for actor Wallace Shawn.

Nearly 20 years after his debut appearance in Pixar’s first Toy Story film, Shawn once again lends his recognizable voice to Rex as he rejoins Woody, Buzz Lightyear and company for another CG-animated adventure, Toy Story That Time Forgot. Debuting tonight on ABC, the dino-centric holiday special centers on the timid T-rex and his triceratops counterpart Trixie (voiced by Kristen Schaal), who find themselves living amid a never-before-played-with line of anthropomorphic action figures called Battlesaurs, who fail to realize that they’re toys.

For Shawn, an accomplished playwright and stage actor who's become known for roles in such films and television series as My Dinner With Andre, The Princess Bride, Clueless and Deep Space Nine, Rex has proved to be his most durable role, as he explained in this interview with Spinoff Online.

Spinoff: What has it meant to have this character in this franchise have such an enduring life and to be able to revisit it from time to time, and come up with a new take and a new twist?

Wallace Shawn: Well, I mean, you're asking the psychological, personal questions? I mean, it's meant that I can live. You know, I have ridden on the back of the dinosaur for a long time. It's obvious if you look at my entry in IMDb, and you can see that, obviously, without it I would probably be even more pitiful than I am today!

Is there a creative kick that you get every time you get a new opportunity to play Rex? Is there something fun in it for you, whenever you get a new script?

Well, I've done it with a lot of different directors now, and of course each one has a very distinctive way of directing – and, of course, toys don't age, really. Theoretically they can get scuffed and tarnished and even destroyed, but so far that hasn't been an element in the stories. So the actor declines into senility and deterioration, but the toy remains in around, well, 1994 – so, pretty mint condition. I mean, if you really look at the toys in this latest episode and look at Rex, he looks just the way he did before. So there's a challenge there. Obviously my own senility and deterioration shouldn't really be a part of the character, so that takes work.

What are your memories of when this character and the original Toy Story project very first came to you? Do you remember the approach and how you felt about it as you got into it and saw this groundbreaking project taking flight?

Well, I have a kind of secret life as a – let's be honest – a writer of some kind of bizarre, almost incomprehensible, weird type of theater, and I wrote a one-person play that I performed myself in San Francisco in around 1990 or '91. And afterwards various people came up to me and spoke to me, and spoke about the subject matter of the play, which had to do with privilege and lack of privilege. And it was a rather grim play, because in real life I am a rather grim person, although I can pretend to be cheerful. But in the crowd of people speaking with me, a strange young man appeared holding a plastic dinosaur and he said, "I'm John Lassiter and I would like you to have this dinosaur, because I plan to ask you to appear in an animated film that has to do with this dinosaur." So I just thought, obviously, that he was a lunatic.

But then it turned out he was for real, and I met all the other delightful people at Pixar. I thought, "What lovely people!" Then we did the first movie, and I thought, "What fun! And how amazingly careful these people are: They're not just tossing this off. They're absolutely passionate about it. They're very, very serious about this cartoon." Then, lo and behold, when I saw what they did, I was flabbergasted by the skill that they had. I was blown away. Of course, we still didn't know that it was going to go on and on, because after all there are many great works – Hamlet or King Lear – with absolutely no sequels, even though they're quite skillfully written. Who knew that it would go on and on and on? That people would connect to these characters in that way?

You've got such an interesting and diverse sort of cinematic legacy, along with the great theater work that you've done. Do you find a lot of crossover in fans, where people say, "I loved My Dinner with Andre, I loved you in Clueless, I loved you in The Princess Bride, I loved you in Toy Story”? Or has Toy Story started to overwhelm some of that other work?

I would say most people who stop me on the street know me for one thing or the other, and they have no idea about anything but the one thing. Only a few show business fanatics sort of know all of those different things. Otherwise, most people don't really follow it in that way. They don't know the names of the actors, or what else they've done.

Do you have a lot of parents approaching you while telling their children, "This is Rex"?

That happens a very great deal, and the children are looking totally puzzled and bored. They don't know what parents are talking about. And the parents then have to go into a very boring explanation, "Well, he's not really a dinosaur, but his voice is used ..." And the kids are sort of thinking, "Can we go have some ice cream now, or …?"

Toy Story That Time Forgot airs tonight at 8 ET/PT on ABC.