[[quoteright:300:https://static.tvtropes.org/pmwiki/pub/images/doctor_x_8206.jpg]]
A 1932 mystery-horror-comedy film directed by Creator/MichaelCurtiz, starring Lee Tracy, Creator/LionelAtwill, and Creator/FayWray.
It follows New York newspaperman Lee Taylor (Tracy) as he covers the investigation of a series of full-moon murders in which victims are strangled, cut with a scalpel, and partially cannibalized. Evidence points to the Academy of Surgical Research, where five scientists -- including the director, Dr. Xavier (Atwill) -- have remained to continue their research while the students are on holiday.
Desperate to protect the reputation of his institution, Xavier strikes a bargain with the police: he will bring the suspects to his Long Island mansion and monitor their vital signs as they watch staged reenactments of the crimes. If he can discover the killer within 48 hours, his name and the Academy's will not be revealed to the newspapers in connection with the murders.
Lee will have nothing of this. He reports the story anyway, and secretly follows the investigation right to the mansion. Too bad Xavier's daughter, Joan (Wray), already recognizes him...
''Doctor X'' was shot in both black-and-white and Technicolor; it was one of the last films to use the two-strip Technicolor process. The color version was believed to be lost until 1978, when a print was discovered in Jack Warner's personal collection. This, in its restored form, is now considered the definitive print, and for over 30 years was the only version of the film available until an HD restoration of the black-and-white version was included on the 2021 Blu-ray release as a bonus feature.
An InNameOnly sequel, ''The Return of Dr. X'', was filmed in 1939. It starred Creator/HumphreyBogart.
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!!Tropes:
* AlternateMonochromeVersion: [[ZigZaggingTrope It's complicated]]; the film was shot simultaneously in both black-and-white and two-color Technicolor cuts. When the movie saw syndication to TV in the 1950's, only the black-and-white version was present due to the color version appearing to have become lost, but a print was eventually found in 1978 and successfully preserved. For decades, this color version effectively became the definitive print of the film when it came to home media distribution, and it wasn't until 2021 that an HD restoration of the original black-and-white cut saw wider distribution as a Blu-Ray bonus feature.
* ArtificialLimbs: Wells's hand.
* BeachEpisode: Lee and Joan have a non-plot-related conversation on the beach in the middle of the film, solely to get in a bit of comic relief (from him) and {{Fanservice}} (from her).
* BeatStillMyHeart: Wells's experiment, a heart kept alive in a jar.
* BullyAndWimpPairing: The servants have shades of this. Otto is a petty {{sadist}} who takes every opportunity to scare high-strung Mamie -- and then they're called on to reenact the killings together.
* CatchPhrase: Lee's "''Bad'' luck!"
* CreepyRedHerring: Every single one of the scientists seem ObviouslyEvil and have the trappings of stereotypical mad scientists, with the exception of Dr. Xavier himself. [[spoiler: This, naturally, may lead the viewer to predict that Xavier is the killer, but he's not: it was one of the weirdos after all.]]
* DeadlyPrank: Inverted. An ExplosiveCigar saves Lee's life by startling the killer at a critical moment.
* DemBones: Invoked, when Lee sees a skeleton apparently peeking at him around a corner. We then realize that it's actually being carried by one of the doctors, though Lee remains extremely shaken by the experience, and a few scenes later, starts talking to more skeletons as if they were alive.
* DisabilityAlibi: Other characters determine that Wells can't be the killer because he only has one hand, which isn't consistent with the way the victims were strangled.
* DisneyVillainDeath: Combined, gruesomely, with KillItWithFire.
* DolledUpInstallment: The sequel, ''The Return of Doctor X'', was based on an unrelated short story. What ties the two films together is their AppliedPhlebotinum: synthetic flesh in the original and synthetic blood in the sequel. There's also ''The Revenge of Dr. X'', which barely even qualifies as this trope.
* ElectricJoybuzzer: Averted. A handshake buzzer appears as a running gag (and is eventually even used as a weapon), but it's the realistic, mechanical kind. [[spoiler: It ends up serving as ChekhovsGun, giving Lee the edge to defeat the villain in a brawl.]]
* ForScience: Part of the killer's motivation.
* GPSEvidence: Police narrow the suspect pool considerably when they discover that the scalpel used in the murders must have come from the Academy of Surgical Research.
* HollywoodDarkness: Averted at least twice: when the lights go out during the first reenactment, and in TheTag.
* INeedAFreakingDrink: After the housemaid sees a bad omen in her tea leaves, she refills the teacup with gin. [[TheAlcoholic From a bottle she keeps under her pillow.]]
* ImAHumanitarian: The killer, seemingly.
* InstantSedation: In the form of knockout gas, used on Lee while he is in the room of skeletons.
* IntrepidReporter: A variation. Lee pursues his story relentlessly, but otherwise doesn't fit the character type: he's a skittish NonActionGuy who only stays on the case because of pressure from DaEditor.
* LovableCoward: Lee, though he ends up extremely brave in the movie's climax.
* {{Lunacy}}: All of the killings have happened on nights with a full moon, leading Dr. Xavier to believe that the moon is a trigger for the so-called "Moon Killer". Dr. Rowitz is also studying the psychological effects of the moon and the phenomena of lunacy, which he poetically describes as the counterpart to sunstroke.
* MadScientist: All of the doctors have elements of this, but the killer embodies the trope perfectly.
* MadScientistLaboratory: The secret lab where [[spoiler: Dr. Wells applies his "synthetic flesh".]]
* NoPartyLikeADonnerParty: Implied to be part of two of the doctors' shared backstory. The two of them - and a third guy - survived a shipwreck off Tahiti and were in a life raft. They insist that the third man died and they threw the body overboard.
* ObfuscatingDisability: [[spoiler: The killer embodies this trope in spirit: even though he really does have only one hand, he is able to easily produce a functional, living replacement]].
* OldDarkHouse: The second half of the movie takes place in Dr. Xavier's eerie, poorly-lit mansion in Long Island, where all the characters are stuck until they solve the mystery.
* PornStash: Haines's magazine of "French art," hidden in a book. This is meant to be a KickTheDog moment for him, establishing him as a pervert, though [[ValuesDissonance modern audiences]] would probably find his behaviour a lot more understandable.
* RedHerring: Doctor ''X'', X being the unknown, is likely to make viewers think the killer is Xavier, whose name starts with an X.
* RedRightHand: Three of the five doctors have physical oddities that could potentially mark them as villainous: Haines wears a [[BeardOfEvil goatee]], Rowitz has a DuelingScar and a [[EyepatchOfPower dark]] [[HighClassGlass monocle]], and Duke [[EvilCripple uses a wheelchair and crutches]]. Of the other two, Xavier is ordinary-looking and Wells's one-handedness actually [[DisabilityAlibi exempts him from suspicion]].
* RunningGag: The hand buzzer.
* ScaryFlashlightFace: Used several times (without actual flashlight), especially when Otto is in the shot.
* SerialKiller: The Moon Killer, who has strangled four people on nights of the full moon. The plot revolves around trying to figure out his identity.
%%* ShadowDiscretionShot
* SlidingScaleOfComedyAndHorror: Leans heavily toward the comedic side, [[ShooOutTheClowns except during the climax]].
* SpannerInTheWorks: Lee, during the second reenactment.
* SpiritualPredecessor: To ''Film/MysteryOfTheWaxMuseum''.
* TechnoBabble: Xavier's explanation of the [[LieDetector stress-detecting device]]:
-->''Gentlemen, I am now turning on the hundred-milliampere high-frequency coil. Your pulses are connected with the magnetic rotators, and each variation of your heartbeat reaction is amplified four thousand times. The rotor of the electrostatic machine is connected in multiple series with a bank of glass-plate condensors, and the discharge causes irradiations to the thermal tubes, which, in turn, indicate your increased pulse rate and nerve reactions.''
* ThrowItIn: The film is full of fluffed lines and obvious ad-libbing.
* ThrowingOffTheDisability:
** Duke is briefly able to walk unaided during the first reenactment. [[spoiler:This is immediately recognized as a temporary result of extreme stress and has no further impact on the plot.]]
** The killer [[spoiler:restores his missing hand with artificial flesh]].
* TrailersAlwaysLie: The original marketing depicted the film as a comedy-thriller-romance, deliberately concealing the substantial horror element.
* {{Undercrank}}: Used, fairly subtly, in the final fight scene.
* WakingUpAtTheMorgue: Played with. Lee hides in the morgue by posing as a corpse, but then behaves as though he hadn't expected to be there. [[RuleOfFunny And where did the toe tag come from?]]
* WellIntentionedExtremist: "I'll make a crippled world whole again!"
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