The creative team of “The O.C.” reunited Sunday at the ATX Television Festival.

Series creator Josh Schwartz sat on a panel with exec producer Stephanie Savage, writer Leila Gerstein and music supervisor Alexandra Patsavas at the Austin, Texas TV fest to discuss the hit teen drama, which ran for four seasons on Fox and ended nine years ago.

The panelists revealed behind-the-scenes tidbits from “The O.C.” Here’s what we learned…

1. Peter Gallagher was the first person cast on the show.

“The first person we cast on the show was Peter Gallagher as Sandy Cohen,” Schwartz revealed. “We wanted to send the message that this was a show that could be for adults, as much as for kids.”

2. The famous line “welcome to the O.C., b-tch” was inspired by water polo players at USC where Schwartz went to school — and so was the show’s title.

The most famous line of the series, uttered by Luke (Chris Carmack) to Ryan (Ben McKenzie), came from Schwartz, who was playfully making fun of the water polo players at USC.

“When I was at SC, there were all these waterpolo guys that refer to Orange County as ‘the O.C.’…as if they were referring to ‘the LBC,'” Schwartz said, laughing that Orange County is not nearly as hard as Long Beach, but the blonde athletes definitely thought it was.

“It was always a bit of an ironic title for us,” Schwartz said.

3. Josh Schwartz never celebrated Chrismukkah.

“It’s not a holiday that we celebrated,” the show creator said about his childhood. So how did the famous TV holiday come about?

“It felt like it really spoke to what we were trying to do with the show,” Schwartz said. “We had a lot of Judaism on the show,” he said, bringing up the Passover sedar scene from Season 1.

Schwartz said that Chrismakkah really emphasized “the idea is that Sandy had married the ultimate shiksa goddess.”

He cracked, “It was a way to get even more presents!”

4. The Cohens were originally named the Newmans.

Stephanie Savage joked that the core family got a little bit more Jewish as the show was developed. Asked how Fox felt about the “whiny Jews” at the center of the show, Savage laughed that the network was “medium okay” with it.

5. Arcade Fire was the one band that Josh Schwartz wanted to feature on “The O.C.,” but never did.

Not getting Arcade Fire on the show is still a sore subject for Schwartz.

“The O.C.’s” music supervisor Alexandra Patsavas was on the panel and spoke about all the great artists that the show did get. The panel agreed that Imogen Heap’s “Hide and Seek” is one of their favorite moments from the entire series.

6. Kailtin Cooper was originally played by Shailene Woodley (in case you forgot).

When Marissa’s little sister came back all grown up, she was played by Willa Holland, but Shailene Woodley originally played the part in a recurring role in the first season.

“Where is Shailene?” Schwartz joked of the actress who’s gone onto star in the “Divergent” series, among other big blockbusters. “I think Shailene’s doing just fine,” he added.

Savage shared that a young Woodley sent the writers a hand-written note and a drawing of Seth’s toy horse when she was no longer on the show.

7. The writers still think about killing off Mischa Barton.

“It’s complicated. There were a lot of factors involve and it was something we really wrestled with,” Schwartz said. “There were reasons both creative and just in terms for the show itself and where we were with the network.”

“It’s something we still wrestle with,” he admitted, adding that he got lots of “anger and fan art.”

8. The writers loved Taylor Townsend.

Autumn Reeser’s character made her debut in Season 3 and became a series regular in Season 4, following Marissa’s (Mischa Barton) death.

“The writers loved writing for Taylor Townsend,” said Leila Gerstein, writer on “The O.C.” who went on to create the CW’s “Hart of Dixie” with Rachel Bilson. “She was so annoying and so delicious,” Gerstein continued, speaking about Taylor Townsend. “We as a group fell in love with her and we were like, we have to keep her around.”

9. Doing more than four seasons was never a strong possibility.

Schwartz said he knew that Season 4 was going to be it.

“Going into it, we had a pretty good sense that was going to be a final season, so it was very freeing creatively,” Schwartz said. “We took some chances that we probably would have felt uncomfortable doing before that.”

While the team didn’t ever strongly consider a fifth season, Savage explained that the fourth season was a more adult version of “The O.C.,” so the writers and producers began to understand what a more mature version of the series going forward could have been. Savage noted that transitioning teen dramas is not easy, after they graduate high school. “Once we were in Season 4, we realized we couldn’t do this forever,” she said.

10. “The Valley” was never going to be a real spinoff.

“We got really into ‘The Valley,'” Schwartz said of the show-within-a-show parody. Asked if he ever considered doing a real spinoff series, Schwartz joked that he planned 14 seasons of “The Valley.”

While “The Valley” isn’t coming to TV any time soon, Schwartz predicted where the next big teen drama may land.

“I don’t know that the next great teen drama is going to be on network [television],” he said. “I think you’re going to find it somewhere else — something else that starts with ‘N’ that’s not ‘network.'”