Now they'll all come together to continue – and conclude – the saga originally plotted in the All Souls trilogy of novels by Deborah Harkness.
Our very own RadioTimes.com review for the final run notes: "Overall, this third and final series will deliver what fans have been waiting for.
"By the time the credits roll there’ll be smiles on faces – and possibly a few tears – with all the loose ends neatly wrapped up and our heroes left in a fairly satisfying position."
So, read on for everything you need to know about the cast and characters of Sky's A Discovery of Witches.
A Discovery of Witches season 3 cast: Full list of characters
Teresa Palmer plays Diana Bishop
Who is Diana Bishop? Diana is a historian who tried to escape her lineage as a witch, but the supernatural world found her when she stumbled upon a bewitched manuscript in Oxford University's Bodleian Library. She formed a controversial alliance with ancient vampire Matthew Clairmont which ultimately blossomed into love, risking her life to save his in the season one finale before travelling back in time several centuries to take refuge from their pursuers.
In season three, she's back in the present day and facing new threats from the Congregation, while also dealing with personal grief and her newfound pregnancy.
What else has Teresa Palmer been in? Palmer has starred in the main cast of several feature films including zombie comedy Warm Bodies, crime thriller Triple 9, horror flick Lights Out and war epic Hacksaw Ridge. Most recently, she played the lead role in Ride Like A Girl, the biopic about jockey Michelle Payne, first woman to win the Melbourne Cup in 2015.
Matthew Goode plays Matthew Clairmont
Who is Matthew Clairmont? Clairmont is an ancient vampire who forms an alliance with witch Diana Bishop, despite their species traditionally being at odds with each other. He is gravely concerned about the declining fortunes of vampires, witches and demons, all of whom are becoming less powerful in the supernatural world. His relationship with Diana eventually becomes romantic and he flees with her to 16th century London, later returning to the present day to finally save his race from extinction.
What else has Matthew Goode been in? Goode is a familiar face to fans of British telly, with recent roles in ITV's Downton Abbey, Netflix's The Crown and BBC One's Ordeal by Innocence. Across the pond, he played Finn Polmar in legal drama The Good Wife and portrayed Ozymandias in the Hollywood adaptation of Alan Moore's Watchmen.
Steven Cree plays Gallowglass de Clermont
Steven Cree as Gallowglass in A Discovery of Witches season 3 (Sky)Who is Gallowglass de Clermont? Gallowglass is a member of the vampiric de Clermont family and the nephew of Matthew. He is a ferocious warrior but also has a softer side and is welcoming to Diana upon her arrival in the distant past. Back in the present day, he's lived another 400 years and has a darker side than before.
What else has Steven Cree been in? Steven Cree has played Ian Murray on the fantasy drama Outlander since 2015, with more recent projects being ITV's Deep Water and Sky One thriller COBRA, starring Robert Carlyle. On the big screen, he recently appeared in action blockbuster Terminator: Dark Fate, where he played Rigby.
Paul Rhys plays Andrew Hubbard
Who is Andrew Hubbard? Hubbard is a vampire who rules the supernatural creatures of London in the 16th century. He has a complicated relationship with Matthew and takes great interest in Diana. Later, in the present day he still tends to his "flock" in the modern world.
What else has Paul Rhys been in? Rhys has previously appeared in Da Vinci's Demons and ITV's Victoria, where he played Sir John Conroy. This isn't his first time as a vampire, either - he played legendary bloodsucker Ivan in Being Human.
Edward Bluemel plays Marcus Whitmore
Who is Marcus Whitmore? Marcus is the vampire son of Matthew as well as a trained doctor. He saved Diana's life in season one by administering a crucial blood transfusion and his father made him leader of the Knights of Lazarus shortly after. He remained in the present day following Matthew and Diana's timewalk to the 16th century.
What else has Edward Bluemel been in? Bluemel broke out on ITV's short-lived period drama The Halcyon, before going on to play Maeve's brother, Sean, in Netflix's Sex Education, and Hugo in BBC One's Killing Eve.
Malin Buska plays Satu Järvinen
Who is Satu Järvinen? Satu is a Finnish witch and a member of the congregation of witches who have their sights set on Diana and Matthew. In the first season, Satu abducts and attempts to torture Diana, but her attempts backfire and she winds up losing her magical powers. Later, she begins to work towards her own ends rather than those of Peter Knox.
What else has Malin Buska been in? Buska hails from Sweden and has primarily worked on projects based in Scandinavian countries.
Aiysha Hart plays Miriam Shephard
Who is Miriam Shephard? Miriam is a vampire who works closely with Matthew and Marcus on their DNA research in Oxford.
What else has Aiysha Hart been in? Hart has previously featured in BBC One's fantasy drama Atlantis, where she played Ariadne. More recently, she portrayed DS Sam Railston across three series of corruption thriller Line of Duty.
Peter McDonald plays Baldwin de Clermont
Who is Baldwin de Clermont? Baldwin is the vampire head of the de Clermont family, and Matthew's older brother who disapproves of his relationship with Diana.
What else as Peter McDonald been in? McDonald takes over the role of Baldwin from Trystan Gravelle, who played the part in seasons one and two of A Discovery of Witches.
He has appeared in TV series like Spooks, The Last Kingdom, No Offence, Thirteen and The Dublin Murders.
Owen Teale plays Peter Knox
Who is Peter Knox? Knox is a high-ranking member of the Congregation who disapproves of the alliance between Diana and Matthew, at one point accusing the vampire of kidnapping her. In season three his schemes are revealed, casting him out but making him more dangerous than ever.
What else has Owen Teale been in? Game of Thrones fans will recognise Teale as Ser Alliser Thorne on the fantasy drama series, while he was also a regular face on Ruth Jones' sitcom Stella on Sky One.
Alex Kingston plays Sarah Bishop
Who is Sarah Bishop? Sarah is Diana's aunt who looked after her after the death of her parents. She too is a magic user and tries to help Diana control her abilities.
What else has Alex Kingston been in? Kingston is perhaps best known as River Song, a recurring character from the modern series of Doctor Who and a fan-favourite. Previously, she played Dr Elizabeth Corday on the medical drama ER. Most recently, she starred opposite Kate Beckinsale in ITV drama The Widow.
Trevor Eve plays Gerbert d'Aurillac
Who is Gerbert d'Aurillac? Gerbert is one of the show's most sinister antagonists, who wishes to abduct Diana for his own nefarious purposes. While working towards this goal, he strikes a deal with the witch Satu, and later convinces Peter Knox to conspire with him too.
What else has Trevor Eve been in? Eve is best known for leading the cast of crime dramas Shoestring and Waking The Dead, the latter of which ran for almost 100 episodes. More recently, he has appeared in ITV's Unforgotten and Sky thriller Strike Back.
Lindsay Duncan plays Ysabeau de Clermont
Who is Ysabeau de Clermont? Ysabeau is the mother of Matthew Clairmont, herself an ancient vampire. She despises witches and so initially disapproves of Matthew's relationship with Diana, but soon sides with the would-be couple against their growing list of enemies.
What else has Lindsay Duncan been in? No stranger to the world of fantasy, Duncan's recent projects include iconic Doctor Who episode The Waters of Mars, BBC One's Merlin and most recently His Dark Materials, where she voiced the daemon Octavia. Duncan has also enjoyed recurring roles in BBC dramas Rome and Sherlock.
Toby Regbo plays Jack Blackfriars
Who is Jack Blackfriars? The young boy Diana and Matthew adopted in the 1600s, who later grew into a young man before being turned into a vampire and mentored by Father Hubbard. He suffers from the violent mania called blood rage.
What else has Toby Regbo been in? Regbo is probably best known for his role as Æthelred, Lord of the Mercians in The Last Kingdom, and he's also appeared in Reign, Medici: Masters of Florence, Fantastic Beasts: The Crimes of Grindelwald and Harry Potter and the Deathly Hallows (in both cases, playing young Dumbledore).
Adelle Leonce plays Phoebe Taylor
Who is Phoebe Taylor? A former employee of Sotheby's auction house, and Marcus' love interest who gets swept up into the de Clermonts' world.
What else has Adelle Leonce been in? Leonce has previously appeared in series like Black Mirror, Strike, Silent Witness, Death in Paradise and the US remake of Shameless.
Olivier Huband plays Fernando Gonçalves
Who is Fernando Gonçalves? The partner of Matthew's late brother Hugh de Clermont, Fernando is a 2,000-year-old vampire who has a complicated connection to the de Clermont family.
What else has Olivier Huband been in? Huband has previously appeared in I Hate Suzie, Informer, Mission Impossible: Fallout and Becoming Elizabeth among other roles.
Gregg Chilingirian plays Domenico Michele
Who is Domenico? A vampire from Venice who has often teamed up with Gerbert to take down the de Clermonts.
What else has Gregg Chilingirian been in? Chilingirian has appeared in the likes of Being Human, Scott & Bailey, Waking the Dead, 126.96.36.199, Inside Men and The One. He was recently cast in Amazon fantasy series The Wheel of Time.
Tanya Moodie plays Agatha Wilson
Who is Agatha Wilson? A daemon member of the Congregation, who you underestimate at your peril.
What else has Tanya Moodie been in? Moodie is probably best known for her role as the high-achieving Meg in Motherland, and has also appeared in This Time with Alan Partridge, The Mallorca Files, Sherlock, Dicte: Crime Reporter, The Clinic, Silent Witness and many more.
Ivanno Jeremiah plays Christopher Roberts
Who is Christopher Roberts? Christopher is a scientist and former friend of Diana (Teresa Palmer) who hasn't seen her in quite some time.
What else has Ivanno Jeremiah been in? Jeremiah is best known for his major role as Max in Channel 4's Humans, with other projects including Doctor Who, Black Mirror, Cold Feet, The Hollow Crown and Jury.
Jacob Ifan plays Benjamin Fuchs
Who is Benjamin Fuchs? A vampire turned by Matthew in the 12th Century, Benjamin is a sworn enemy of the de Clermonts.
What else has Jacob Ifan been in? Ifan has previously appeared in Cuffs, Hinterland, The Accident and Bang among other projects.
Daniel Ezra plays Nathaniel Wilson
Who is Nathaniel Wilson? The daemon son of Agatha Wilson, who defied the Congregation by falling in love with witch-born daemon Sophie.
What else has Daniel Ezra been in? Ezra has also appeared in Prime Suspect 1973, The Missing, Undercover, Prey, Murdered by My Boyfriend and All American among other TV shows.
Aisling Loftus plays Sophie Wilson
Who is Sophie Wilson? A daemon born to a long line of witches, Sophie hides her heritage due to stigma about mixing of the different creature races. Later, she gives birth to a daughter with Daniel.
What else has Aisling Loftus been in? Loftus played one of Sophie's ancestors in A Discovery of Witches season two alongside her main role. Outside of the series, she's appeared in War & Peace, Broken, Mr Selfridge, Good Cop and Five Daughters.
Greg McHugh plays Hamish Osborne
Who is Hamish Osborne? A close friend to Matthew, Hamish is a well-off daemon.
What else has Greg McHugh been in? McHugh has appeared in the likes of The A Word, Fresh Meat, Guilt, The Cockfields, Marvellous and Gary: Tank Commander
A Discovery of Witches returns on Friday 7th January on Sky Max.
Looking for something else to watch? Check out our TV Guide to see what's on tonight.