Twelve actors have been added to the cast of Joss Whedon’s upcoming HBO sci-fi drama series, “The Nevers,” including Olivia Williams (“Counterpart”), James Norton (“McMafia”), Tom Riley (“Dark Heart”), Ann Skelly (“Death and Nightingales”), Ben Chaplin (“The Thin Red Line”), Pip Torrens (“The Crown”), Zackary Momoh (“Seven Seconds”), Amy Manson (“Torchwood”), Nick Frost (“Fighting With My Family”), Rochelle Neil (“Terminator: Dark Fate”), Eleanor Tomlinson (“Poldark”) and Denis O’Hare (“Big Little Lies,” “Late Night”).

And we have the official character descriptions for the newly added stars, who join previously announced lead Laura Donnelly, who plays Amalia True on the series about “a gang of Victorian women who find themselves with unusual abilities, relentless enemies, and a mission that might change the world.”

“The Nevers” will be written, directed, executive produced and showrun by the “Buffy the Vampire Slayer” creator himself. “Buffy” vets Jane Espenson and Doug Petrie are executive producing and writing “The Nevers” alongside Whedon, with Bernie Caulfield also executive producing.

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Production began this summer in London. No premiere date has been set for the series yet.

Read the character descriptions below, including the previously released listing for Donnelly’s Amalia.

Laura Donnelly as Amalia True – The most reckless, impulsive, emotionally damaged hero of her time. A menace to stuffy Victorian society, she would die for the cause and kill for a drink.

Olivia Williams as Lavinia Bidlow – A wealthy spinster and champion of the “Touched”, Lavinia funds the Orphanage (where Amalia and many of the Touched live) through her vast family fortune. She is stern and old-fashioned, but as strong-willed and clever as anyone she confronts.

James Norton as Hugo Swann – A pansexual posh boy whose charm has about five years left on its lease. He runs a secret club and a side trade in blackmail. He’s devoted to fulfilling everyone’s worst impression of him – and fascinated by the Touched.

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Tom Riley as Augustus “Augie” Bidlow – A sweet, disarming nerd and Lavinia’s younger brother. A keen ornithologist, Augie is happy to let his older sister take the reins of the family fortune. He finds the Touched unnerving, but is drawn to them by his increasing infatuation with Miss Adair, and by the schemes of his nefarious best friend, Hugo.

Ann Skelly as Penance Adair – Amalia’s dearest friend, and one of the first women to join her cause. A devout – yet heretically progressive – Irish girl, Penance has genius for invention. She is delighted by her power, and her default is love and acceptance. But she’s firm in her moral sense, and will be guided by what’s right over what’s expedient every time.

Ben Chaplin as Detective Frank Mundi – Big, gruff, and deeply moral, Detective Mundi trusts no one, least of all himself: his reputation for sudden violence (and excessive drink) is not unwarranted. Frank finds himself caught between the powerful, who ignore the the laws of the land, and newly empowered, who ignore the laws of physics.

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Pip Torrens as Lord Massen – Staunch, unflappable and merciless in his defense of the British Empire, this former General, now Peer, may be the only man who sees clearly what havoc these few strange people can wreak upon the established order. Which he will protect, one way or another.

Zackary Momoh as Doctor Horatio Cousens – One of the few successful West Indian physicians in London. Married with a young son, Horatio’s fortunes took a dark turn when he met Amalia and discovered his own ability. Now he works with her, and with the Beggar King, those who don’t care who is or isn’t “different.”

Amy Manson as Maladie – Committed by her husband (and genuinely unstable), she’s been warped by a power she can’t understand, and tortured by doctors intent on finding its source. She now lives underground, runs a gang and is on an infamous murder spree. She affects a theatrical parody of a bedlam waif, but mad as she is, she’s a woman with a purpose.

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Nick Frost as Declan Orrun, aka The Beggar King – Charismatic and brutal, Declan runs – or has a piece of – most of the low-level criminal activity in the city. He’s perfectly happy to help Amalia and her cause – and equally happy to sell them out. He backs winners, and the Touched are long odds.

Rochelle Neil as Annie Carbey, aka Bonfire – Annie is a career criminal who landed the ability to control fire and is happy to hire it out. Came up rough, stayed that way, but she’s neither impulsive nor cruel – just looking out for herself. No matter who she works with or for, Annie trusts only Annie, and the fire.

Eleanor Tomlinson as Mary Brighton – Gentle but surprisingly resilient, Mary pursued her dream of singing on stage. A disappointing career and a broken engagement haven’t diminished her spirit. She’s going to be great. She’s going to be very surprised how.

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Denis O’Hare as Dr. Edmund Hague – A gifted American surgeon, he uses his skills in the coldest, most brutal way possible. But it’s all in the name of progress!