Complete Monster: Caulker's Mate Cornelius Hickey is a ruthless, ratlike man with a penchant for manipulating others. Murdering his rival Irving, Hickey frames the local Inuit people, resulting in their massacre. Leading a mutiny against Captain Crozier, Hickey slaughters all who oppose him and tortures the ship's doctor Goodsir, so he cuts them up for Hickey and others to cannibalize. Mocking Crozier by killing his second-in-command and presenting Crozier with the man's right arm, Hickey attempts to murder Crozier and keep Goodsir in line via increased torture until the man kills himself to escape. Hickey ends up being so vile that even the monstrous, soul devouring Tuunbaq on the arctic ice finds his soul too unclean to devour.
Too Bleak, Stopped Caring: If knowing that it's based on a real-life Arctic expedition that ended in total failure doesn't cause this to set in, the sheer number of unlikable characters (and the few decent characters dying or hitting the Despair Event Horizon early on) and the constant jerking on their chains will.
For the first three episodes the main characters are analogous to the cast of Star Trek: The Original Series. Producer Ridley Scott emphasised the similarity between Victorian explorers and modern astronauts to the degree that Franklin provides a Shout-Out to the Starfleet mission statement in the first episode. Franklin is the arrogant but loveable Captain Kirk, Crozier the Only Sane Man is Spock because he puts logic before personal glory, The MedicBadass Bookworm Goodsir is Bones, Longhaired Pretty Boy Fitzjames fills a similar role to the original Mr. Fanservice Chekhov, and the elderly but resourceful Blanky is Scotty. The peaceful Inuit are mistaken for The Savage Indian in a similar way the Klingons from the new film series were misunderstood as warlike aggressors.
The Tuunbaq is a physical representation of the difficulties and horrors that confronted the Franklin Expedition. It is exactly as relentless and unforgiving as the Arctic itself. It seems as though its actions are done with a view to compound the Expedition's misery solely For the Evulz. For example, had the tinned food not been lead poisoned and properly sealed Franklin's men might have had just enough strength to make it to mainland Canada. Finally, Franklin's men were — from the locations of their last campsites — able to find the Northwest Passage, completing their objective and in some senses beating the environment and their difficulties but, as with what it costs them in the series to finally kill the Tuunbaq, only in a manner that makes their eventual triumph a Pyrrhic Victory.
Award Snub: Despite its critical success, the show failed to gain any Emmy nominations.
Awesome Music: Marcus Fjellström's opening theme, a haunting piece for piano and percussion that bespeaks an eerie cold and loneliness.
Big-Lipped Alligator Moment: The golden chains pierced through Lt. Little's face in the final episode. Doesn't matter how historically accurate it is, it just looks weird as hell, comes completely out of nowhere, never gets even an attempt at explanation (where did he even get these?), and can easily ruin the otherwise somber atmosphere of the scene.
Complete Monster: "Cornelius Hickey" is in truth a stowaway who murdered the real Cornelius Hickey and stole his identity. On the HMS Terror, Hickey blackmails a fellow sailor into having sex with him and attempts to murder the Inuit shaman "Lady Silence". Abandoning the HMS Terror when it gets stuck on Arctic ice, Hickey murders his own hunting party and frames an innocent Inuit family for the deed, resulting in their deaths, children included. After successfully stealing a boat and supplies from the crew and kidnapping Dr. Henry "Harry" Goodsir, Hickey kills his own sexual partner and forces Goodsir to butcher the body for Hickey and his fellow mutineers to eat, threatening to kill other members of his party if Goodsir doesn't comply with Hickey's demands. Finding Goodsir to have committed suicide, Hickey mutilates Goodsir's corpse and forces Crozier to partake in the cannibalism before having him and his own men in chains to use as bait for the Tuunbaq while Hickey attempts to control the beast. The Tuunbaq ultimately dies trying to devour him because of how utterly vile Hickey's soul truly was.
Crosses the Line Twice: Franklin getting his leg ripped off by the creature and set plummeting down an ice hole to his death? Horrifying. His severed leg then tidied up and buried in a full-size coffin, in lieu of anything else to bury? Bizarrely and darkly funny, especially since Goodsir struggles to decide how to place the leg in the coffin.
Charles Dickens didn't promote the fundraising of the rescue expedition on Lady Jane's behalf as shown in the series. However Franklinites appreciate The Cameo as a reference to his later public feud with Dr. John Rae, the man who first made claims that the survivors had resorted to cannibalism (which Dickens refused to believe and found in poor taste).
In the same vein, Ross's Inuktitut interpreter in the show is never named, but is universally taken as a reference to Rae due to being a white, bearded man with a Scottish accent, even though Rae didn't search for the expedition with Ross. Rae spoke some Inuktitut, but it was limited and he employed his own native translators.
Crozier and Fitzjames are a very popular pairing among the fandom due to the eventual tenderness their friendship takes on. This may have been intentional — according to Jared Harris and Tobias Menzies, a lot of their later scenes together were filmed "like love scenes", with minimal crew to interfere with their performances.
After Fitzjames's confession of his origins in episode 8, the crew left the camera running, prompting Menzies (according to Harris) to worry that he'd forgotten a line and whisper "What are we supposed to be doing?" Harris replied, "I think we're supposed to make out?"
Improved Second Attempt: The series solves the book's problem of Hickey being a psychopathic villain while also being based on a real life and blameless man, by adding the twist that show "Hickey" is in fact an impostor who murdered the real man and stole his identity.
Maybe Magic, Maybe Mundane: Borders on Wild Mass Guess. After Franklin dies Jane Franklin says she can 'feel' her husband's spirit calling out to her. Considering that souls are said to exist and the Tuunbaq did not eat Franklin's soul, perhaps Franklin's soul did go back to his wife to beg her to help his men get home.
Moral Event Horizon: You can take your pick with Cornelius Hickey. Is it when he murders Farr, Irving and an entire Inuit family, including a child, just to undermine Crozier, and then subsequently mutilates Irving's body? Is it when he kidnaps Goodsir? The hint that he found, dug up, looted and devoured Fitzjames' body? Is it when he ruthlessly kills his former lover Billy for being ill and then eats his body? Maybe it's when he butchers Goodsir's body, leaving him out on a slab like an undignified hunk of meat, or when he forces Crozier to partake. Or when he knocks out his henchman Tozer and forces him, alongside the others, into a suicidal mission. However, it might have come before all that... when he killed the real Cornelius Hickey and stole his identity just for quick passage.
Ooh, Me Accent's Slipping: While Jared Harris does a decent Northern Irish accent most of the time, occasionally it sounds much more southern. Crozier was from Banbridge, 25 miles away from Belfast, but Jared Harris's dad Richard was from Limerick, in the southwest.
Special Effects Failure: The show avoids this for almost its entire runtime, but the scene of Hickey being ripped in half at the waist by the Tuunbaq in the final episode just looks bad, leaving a bit of a sour taste after ten episodes of nearly flawless special effects.
Tear Jerker: The entire show. The very first scene tells us that the expedition is missing and probably dead, so we know it is not going to end happily. Most of the men have problems, but most of them are not bad people. It is made even worse by the fact that it becomes increasingly clear that as a group, most care deeply for one another. As their situation becomes more desperate and their true selves are revealed, most try to fight against their own fears and weaknesses. Most of the men try to hang together and keep military discipline in increasingly hopeless circumstances. Yet despite all their suffering, all their attempts to make it through, it turns out to be All for Nothing.
Too Bleak, Stopped Caring: The villains are ravening psychopaths or unknowable eldritch horrors, while most of the rest of the cast tend to be very flawed. Adding to the fact that the whole expedition is Doomed by Canon, it can make some viewers reluctant to get invested in the story.
Unintentional Uncanny Valley: The Tuunbaq was deliberately given human qualities, particularly around the face. With how well it blends into the environment and the slow-build up to truly seeing it, it can easily be mistaken for just another polar bear at first, but with something distinctly off. Its eyes are also completely human.
that while the series was true to the book and kept a Giant Space Flea from Nowhere as the threat, he wished they'd just gone with the very real, very dangerous foe of a large polar bear, which would have been just as scary and hewn closer to reality.