Emily Deschanel's Sister Zooey Guest Starred In One Of The Best Bones Episodes

For a show that featured a lot of death, "Bones" sure did have a lot of heart. A series doesn't run for 12 seasons without an effective emotional core, after all, and "Bones" certainly managed to maintain a soft spot, even as Emily Deschanel's Temperance Brennan and David Boreanaz's Agent Seeley Booth inspected some of the most horrific corpses you've ever seen on TV.

One nice behind-the-scenes aspect of the series to offset the ongoing corpse inspections was the fact that the "Bones" cast often included family members of the stars and the show's creator, Hart Hanson. David Boreanaz's father, Dave Roberts, appeared in an uncredited cameo as an FBI agent, while Hanson's own father, Paul, showed up as a vending machine repairman. But it was during one Christmas episode that we got perhaps the most notable family-member appearance in the series.

Yes, even "Bones," with fake cadavers so disgusting they made producers sick, sometimes liked to celebrate the holidays. Indeed, one of the best festive episodes happened to feature Deschanel's younger sister Zooey — who, having co-starred in "Elf," was no stranger to Christmas-themed entertainment. Her brief appearance on "Bones" was, however, a tad less heartwarming than her role on "Elf," beginning as it does with the violent death of a man dressed as Santa Claus. Still, it was a thrill for fans of both the show and Deschanel to see the sisters united in "Bones."

Season 5, episode 10, "The Goop on the Girl" aired on December 10, 2009, and got straight into the festive spirit by blowing up Santa. That is to say, the episode began with a bank robber dressed as old St. Nick accidentally setting off a bomb strapped to his chest. This incinerates the unfortunate individual in a giant ball of fire that ends with a gratuitous shot of a detached eyeball going up in flames. Ho ho ho!

Of course, Seeley Booth and Temperance Brennan are left to get to figure out who this explosive St. Nick might have been after he leaves a nice layer of bodily "goop" on a witness at the scene, hence the episode title. Luckily for Zooey Deschanel, she was not the "girl" in question and didn't have to go anywhere near any festive viscera. Instead, the "New Girl" star played Brennan's second cousin, Margaret Whitesell.

After Brennan gives up on her plans to spend Christmas in El Salvador, she instead spends the holidays with her father (Ryan O'Neal) and Margaret, a long lost relative who, as Booth can't seem to stop pointing out, looks so much like her cousin that she and Brennan could be sisters. (Get it? Cuz they are?) Aside from featuring one of the best guest appearances in "Bones" history, "The Goop on the Girl" (which topped our list of the best "Bones" Christmas episodes) is noteworthy for being the only time the Deschanel sisters have been in the same scripted TV show.

Speaking about her appearance on "Bones" in a behind-the-scenes interview, Zooey Deschanel was clearly happy to have been part of her sister's show, stating, "It is fun for me to be in the 'Bones' world. I love the show I think it's a great show and Emily's always great." The actor also recalled visiting the set prior to her appearance, so she had clearly been close to "Bones" before she was cast in her brief season 5 role. Meanwhile her sister, Emily revealed that their first scene in "Bones" together was the sisters' first time working together professionally since they had appeared in plays together "as kids." She also noted that she and the producers had been trying to get Zooey on the show "for a long time," adding:

"Certainly from the second season on I think we've been trying to figure that out, but she's a busy lady and so it's been hard to get her to actually be in an episode. So it's exciting, I didn't believe it was going to actually happen until it really did."

Interestingly enough, Emily Deschanel mentioned that her sister had been in Belfast prior to shooting her "Bones" scenes. This likely pertained to her filming her role in "Your Highness," the ill-fated David Gordon Green fantasy action-comedy that was shot in Northern Ireland in the summer of 2009 (with Danny McBride and James Franco co-starring). Thankfully, 2009 also saw Zooey Deschanel starring in "500 Days of Summer," a bittersweet anti-Valentine's Day movie that somehow restores your faith in romance and was received much more favorably than "Your Highness" was when it arrived in 2011.