Throughout 9-1-1: Lone Star and featured intense rescues that took place in Austin, Texas. Unfortunately, 9-1-1: Lone Star has since come to an end after five seasons. 9-1-1 lives on, however, and will continue later in the year, with more spinoffs potentially in the works.

Prior to 9-1-1 and 9-1-1: Lone Star, though, Minear collaborated extensively with Whedon. That collaboration started on Angel, the spin-off of Firefly and did the same on Dollhouse. He clearly never forgot those he worked with, however.

11 Doug Savant

Savant Briefly Appeared In Both Firefly and 9-1-1

Savant appeared in Firefly season 1, episode 3, "Bushwhacked." The episode was actually written and directed by 9-1-1 co-creator, Minear. There, Savant played Commander Harken, an officer within The Alliance. As such, he was billed as a polar opposite to Serenity captain Mal Reynolds (Nathan Fillion) when the two crossed paths. Together, they ultimately had to deal with a traumatized, and now murderous, survivor of a Reaver attack. The action culminated in Harken almost being killed by the now-mutilated man, with Mal stepping in to save him. As a result, they formed a begrudging respect for each other.

Over on 9-1-1, Savant played Matthew Clark, the brother of former 9-1-1 dispatcher Abby (Connie Britton). He appeared in two episodes, the first of which was 9-1-1 season 1, episode 3, "Next of Kin." Therein, they clashed over how best to take care of their ailing mother and how Abby had given up on having a normal life on her behalf. He later returned for 9-1-1 season 1, episode 10, "A Whole New You," after their mother ed away. With Abby subsequently deciding to travel around Europe, there was little reason for Savant to reprise the role further.

10 Brigid Brannagh

Brannagh Starred In Multiple Episodes Of Angel Season 2

In Angel, Brannagh played Virginia Bryce, the socialite daughter of a powerful wizard. As such, she first appeared in Angel season 2, episode 6, "Guise Will Be Guise," when Wesley (Alexis Denisof), pretending to be Angel, served as her bodyguard. Despite the initial deception, the pair struck up a relationship that lasted multiple episodes, culminating in Angel season 2, episode 15, "Reprise," when she decided she couldn't cope with Wesley's dangerous, demon-hunting lifestyle. She later starred in 9-1-1: Lone Star season 3, episode 2, "Thin Ice," as the mother of Abe, a young boy who falls into a frozen lake.

9 Sean Maher

Maher Was A Main Character In Firefly

Maher played Simon Tam, a member of the Serenity crew on Firefly. As such, he appeared in all episodes of Firefly's first and only season before returning for the Serenity movie. Though begrudging at first, he eventually becomes one of the Serenity family, alongside his sister, River (Summer Glau) and eventual partner Kaylee (Jewel Staite).

Throughout the run, he also served as the ship's doctor, tending to the frequent wounds the crew received. He later cameoed in 9-1-1 season 1, episode 7, "Full Moon (Creepy AF)," playing Paul, the partner of a man suffering from a particularly vicious tapeworm.

8 Leonard Roberts

Roberts Had A Recurring Role In Buffy The Vampire Slayer Season 4

Roberts ed Sarah Michelle Gellar and company during the divisive Buffy the Vampire Slayer season 4, episode 21, "Primeval," which Riley won.

A Buffy the Vampire Slayer revival is in the works, with Sarah Michelle Gellar set to return and Chloé Zhao on board to direct.

On 9-1-1, Roberts was first credited as Ronnie Cooper in season 3, episode 2, "Sink Or Swim." Cooper serves as the captain of firehouse 136, where Ronda Rousey's Lena Bosko was originally stationed. Initially on hand to help in the wake of a tsunami, Cooper was eventually stated to have gone missing. His whereabouts were revealed in 9-1-1 season 3, episode 3, "The Searchers," when he's found trapped beneath a car and Athena (Angela Bassett) was forced to amputate his arm. Roberts made one more appearance, revealed to still be on duty as captain, later in season 3, episode 8, "Malfunction."

7 Richard Brooks

Brooks Enjoyed A Memorable Guest Star Role In Firefly

In a memorable turn, Brooks appeared in Firefly season 1, episode 10, "Objects In Space." There he played Jubal Early (named after a real figure), an unstable bounty hunter searching for River Tam. In pursuit of that aim, he bested several of the Serenity before being outsmarted and left floating adrift in space.

Brooks later ed 9-1-1 as Chief Simpson, who oversees all LAFD firehouses, including the 118, to whom he eventually awarded medals of valor. He appeared multiple times in 9-1-1 season 7 before also returning in 9-1-1 season 8, episode 7, "Hotshots," to guide Bobby (Peter Krause).

6 Harry Groener

Groener Played The Big Bad In Buffy The Vampire Slayer Season 3

First teased in Buffy the Vampire Slayer season 2, The Mayor of Sunnydale became a full-fledged character in season 3. Played to perfection by Groener, he served as the main villain of the season. As such, The Mayor and his minions terrorized the Scooby Gang and even managed to corrupt fellow slayer Faith (Eliza Dushku). After ascending to become a pure demon, he was ultimately destroyed in an explosive trap, though he cameoed in later seasons. In 9-1-1: Lone Star season 3, Groener played Joe, a turtle-saving man who was present for TK's (Ronen Rubinstein) rescue of the boy trapped in a frozen lake.

5 Adam Baldwin

Baldwin Was Another Main Character In Firefly

Baldwin has actually had two Whedonverse credits to his name. The first comes courtesy of the still criminally short-lived Firefly. There he played the gun-toting mercenary Jayne Cobb. Initially, he was not the most trustworthy of Serenity's posse and even betrayed River Tam after she and brother Simon had become valued crew . Over time, however, Jayne found his heart and became as loyal as he was tough. Following Firefly's cancelation, Baldwin crossed over to Angel and played Marcus Hamilton, the villainous emissary of the Senior Partners. As a result, he was ultimately defeated and killed by the titular vampire.

Firefly continued in comic book form via Dark Horse Comics and then BOOM! Studios, as written and drawn by various writers and artists.

Over on 9-1-1: Lone Star, Baldwin played Detective Brian McGregor. He debuted in the role via 9-1-1: Lone Star season 4, episode 15, "Donors." Though initially as surly as his Firefly counterpart, he ended up doing his part to catch of an organ-trafficking ring. In the process, he even saved the life of Grace Ryder (Sierra McClain). He later returned in season 5, episode 8, "The Quiet Ones" helping to answer some of 9-1-1: Lone Star's unanswered questions as Carlos (Rafael L. Silva) seeks to solve his father's murder.

4 D.B. Woodside

Woodside Played A Recurring Role In Buffy The Vampire Slayer Season 7

Woodside debuted as Robin Wood in Buffy the Vampire Slayer season 7, episode 1, "Lessons," when he reopened the infamous Sunnydale High. Initially seeming like little more than a mild-mannered high school principal, he was eventually revealed to be the son of a previous vampire slayer. As such, despite his clashes with Spike (James Marsters), he becomes an ally to the Scooby Gang in their battles with The First. In 9-1-1: Lone Star, he played Trevor Parks, a pastor with whom Tommy Vega (Gina Torres) falls in love. Unfortunately, their romance ended when he had to leave Texas for family reasons.

3 Julie Benz

Benz Made Frequent Appearances In Buffy The Vampire Slayer and Angel

Benz was one of the first to make an appearance in Buffy the Vampire Slayer season 1. Though she was slayed not too long after, the actress was still able to leave her mark on the shared universe via the spin-off show Angel. Revealed to be Angel's sire, Benz's Darla first appeared in flashbacks but was ultimately resurrected in Angel season 1, episode 22, "To Shanshu In L.A." From there, she served as an intermittent foil for Angel (David Boreanaz) across multiple seasons, until she miraculously got pregnant with the widely hated character that is Connor and sacrificed her life for his.

When she eventually did return, she's revealed to be dangerously obsessed with Owen and arrested for tormenting him and his new girlfriend.

Benz debuted on 9-1-1: Lone Star in season 3, episode 1, "The Big Chill," playing Sadie Becker. A neighbor of Owen Strand's (Rob Lowe), she finds herself equally cut off from the rest of Austin, Texas by a freak snowstorm. Also embroiled in Owen's mission to protect some migrants from corrupt police officers seeking to traffic them, she is seemingly established as a potential love interest, but disappeared after 9-1-1: Lone Star season 3, episode 3, "Shock and Thaw." When she eventually did return, she's revealed to be dangerously obsessed with Owen and arrested for tormenting him and his new girlfriend.

2 Amy Acker

Acker Was A Popular Mainstay For The Majority Of Angel

Acker first emerged as Winifred "Fred" Burkle during Angel season 2, and quickly became a main cast member and one of Whedon's most prolific collaborators. She remained as Fred until Angel season 5, episode 15, "A Hole In The World," where she was killed and ultimately resurrected as the goddess Illyria. Following the show's conclusion with the Joss Whedon-penned Angel season 5 finale, Acker ed the main cast of Dollhouse. Given the nature of the show, she embodied several different characters, including Dr. Claire Saunders. She also starred as Beatrice in Whedon's adaptation of Much Ado About Nothing.

As Catherine Harper, Acker debuted in 9-1-1: Lone Star season 3, episode 5, "Child Care." Catherine was the Chief of Staff for the Governor of Texas, who met Owen Strand through a dating app. Though their first date was a tumultuous one, involving chasing down a kidnapper, they eventually got on better and became one of the best 9-1-1 couples. As such, Acker returned for five more episodes, including a dramatic one that saw her targeted in a suspected chemical attack. Ultimately, Owen and Catherine broke up, and she was last referenced as having left Texas for Washington D.C.