Who will be the next character to cross over from ‘Young Sheldon’ to ‘Big Bang Theory’?

Hollywood, Calif. • Sheldon Cooper’s mother, sister, brother and grandmother have all bridged the gap between “The Big Bang Theory” and “Young Sheldon,” so who might be next?

It won’t be a family member. They’ve run out of those. But it might be Sheldon’s (Jim Parsons) best friend. Well, his only friend.

According to creators/executive producers Chuck Lorre and Steve Molaro, Tam Nguyen is the logical choice to make the transition. And it’s very much a possibility.

“For sure,” said Molaro.

“Absolutely,” Lorre agreed. “Oh yeah. We’re very much talking about it.”

For the uninitiated, Sheldon Cooper is the linchpin of “The Big Bang Theory” — a misanthropic genius who struggles to relate to others. “Young Sheldon” flashes back to when his quirks made him a trial for his family and a fish out of water as a 9-year-old high schooler.

“Big Bang Theory” remains a huge hit in its 11th season; “Young Sheldon” is a breakout hit in its first. The two shows were No. 1 and No. 2 in the ratings last week. They wrap up their seasons next Thursday.

The dry sense of humor Tam displays in “Young Sheldon” would translate perfectly to “Big Bang.” Tam and Sheldon have had exchanges like this:

“I also tried to get some uranium and build an atomic engine,” Sheldon says, “but that stuff’s hard to find.”

“Probably for the best,” Tam replies.

And this:

“Hey, I’ve been looking all over for you,” Tam says. “Do you know how popular we are?”

“We?” Sheldon asks.

“Yeah. I put the word out I was helping you with the football stats,” Tam replies. “And since I’m Asian, they bought it.”

Lorre talked as if Tam crossing over from one show to the other is pretty much a done deal, dependent on “organization and planning.” That and coming up with a good idea.

But don’t look for a storyline to start in an episode of “The Big Bang Theory” (Thursdays, 7 p.m., CBS/Channel 2) and then continue on the following episode of “Young Sheldon” (Thursdays, 7:30 p.m., CBS/Channel 2).

Lorre and Molaro — who are executive producers of both shows — acknowledged that it would be a “great idea,” but Lorre added, “I don’t think we’re that organized. … That kind of coordination is not possible.”

Of all the non-family members on “Young Sheldon,” an adult version of Tam (Ryan Phoung) showing up on “Big Bang” certainly seems to make the most sense. He is, again, the only friend Sheldon has.

And, yes, it makes sense that there would be a Vietnamese boy attending an East Texas high school in 1989. “We did a little research,” Lorre said, and learned “there’s a wonderful Vietnamese population on the gulf” — refugees who came to the United States at the end of the Vietnam War.

“After the war, my father was sent to a re-education camp because he fought on the wrong side,” Tam tells the Coopers when he’s invited to dinner in one episode.

“You mean our side,” says George Sr., Sheldon’s father.

“I was trying to be nice,” Tam replies.

(We know that George Sr. died when Sheldon was a teenager, so he won’t be appearing on “BBT.”)

And when Sheldon politely declines Tam’s offer to share his candy, Tam says, “I’m not hungry. The three words you never hear in Vietnam.”

And it makes sense that Tam and Sheldon would become friends, albeit somewhat awkward friends because Sheldon is so, well, awkward.

“We thought that Sheldon is so much outside looking in in this high school,” Lorre said. “And we thought it would be really great if we could find a character who also is struggling to be part of the mainstream. To try and assimilate into this big high school.”

“There’s an age gap, but there’s an experience that they both can bond over,” Lorre said.

Tam won’t be at Sheldon and Amy’s (Mayim Bialik) wedding in the May 10 season finale of “BBT.” But he could show up next season in adult form.

Crossing over

If (when?) an adult version of Tam from “Young Sheldon” appears on “The Big Bang Theory,” it will be the sixth time we’ve seen younger and older versions of the same character on the two shows In addition to Sheldon himself. The others to date are the following:

• Oscar nominee Laurie Metcalf first appeared as Sheldon’s mother, Mary, in the fourth episode of “BBT” and has returned more than a dozen times.

• The younger version of Mary on “Young Sheldon” is played by Metcalf’s real-life daughter, Zoe Perry.

• Courtney Henggeler appeared as Sheldon’s twin sister, Missy, in the 15^th episode of “BBT”; she’s returning for Sheldon and Amy’s wedding on May 10.

• The “Young Sheldon” version of Missy is played by Raegan Revord.

• June Squib played Sheldon’s grandmother, aka Meemaw, in a 2016 episode of “BBT.”

• Annie Potts stars as Meemaw on “Young Sheldon.”

• Montana Jordan stars as Sheldon’s older brother, Georgie, on “Young Sheldon.”

• An older version of Georgie, played by Jerry O’Connell, appeared in the May 3 episode of “The Big Bang Theory” — and he’ll return for the wedding on May 10.