- "Smile, my dear! You know, you're never fully dressed without one!"
- ―Alastor, after seeing Vaggie frown
Alastor is about the same height as Vox, with the two of them standing at 7". He is quite slim, with Kahki colored skin, and sharp yellow teeth. He sports a short red angled bob cut with black cowlicks extending from the top of his head, resembling deer ears, and two small black antlers which can grow in size while in his demonic form.
His eyes, have red scleras, bright red irises, black pupils (which can change into radio dials when in his demon form), and wears a black oval-shaped monocle over his right eye.
Alastor wears a dark red pinstriped coat which is slightly ragged along the bottom, a bright red dress shirt with a black cross on the chest underneath and long burgundy dress pants with matching bright red cuffs.
He is also dressed in a red-knotted bowtie, burgundy gloves, and black pointed-toe boots with red deer hoofprints emblazoned on the soles. Alastor also carries a thin cane with a sentient vintage style microphone attached to it which he uses to play sound effects and broadcast his voice.
Alastor's behavior, mannerisms, and even his voice are similar to an old-fashioned radio announcer; for instance, when he refers to modern television as a "picture show" and refers to Charlie as "charming demon belle". Alastor deviates from the crass nature prominent in Hell in favor of an amiable persona. Thus, he is always smiling and acts politely. He never stops smiling because he believes it shows power and dominance. If a rival were to frown, he would see them as weak.
He is narcissistic, not seeing many people quite up to his level. However, that does not make him reckless. Despite being extremely powerful, Alastor is fully aware that there are other demons and entities that rival him in terms of power, such as the Overlords. For this reason, he is wary around such demons, as they could potentially harm him if he is not careful.
Alastor also seems to have a moral compass against the sexual and begraddled society of Hell, which is actually "not normal". However, he has been noted to be quite sadistic and to have masochistic tendencies, rumored to be cannibalistic and devouring lesser demons. Despite this, he genuinely wants to help Charlie run the Happy Hotel, albeit for his own amusement rather than idealism. Alastor even dismisses the idea that redemption is possible. Nevertheless, he still provides the hotel a staff, and protects Charlie's business from outside threats.
- Demon Transformation: Alastor shares a common trait that every other Demon has, which is the ability to turn into his Full Demon form and back to his default form with ease.
- Bilingualism: Alastor can speak English fluently as well as broken Creole French.
- Cooking: Alastor hints at his ability to create amazing meals at the end of the pilot after mentioning having admired his mother's cooking, specifically her Jambalaya.
- Musical, Dancing, and Theatrical Talent: Alastor is shown to display moderate vocal abilities and excels at dancing (tap, ballet, ballroom) as shown in his reprise in the pilot. He also shows a flair for theatrical showmanship.
- Broadcasting: Even before he died, Alastor excelled at broadcasting what he wants the public to hear over the radio, and he continues to do so in Hell, earning him the title of "The Radio Demon".
- Flexibility: Alastor can position his body into numerous unnatural poses and such without hurting his joints. He has also shown to be able to turn his head 180°.
- Wide Intellect: Alastor is shown to be quite the cunning individual, which resulted to him becoming one of the most powerful Overlords in Hell through his tricks and deal-making. He always strategizes and thinks ahead before proceeding to execute a plan.
- Shadow Manipulation: Alastor is able to summon shadows and manipulate them into doing his bidding.
- Eldritch Control: Alastor has shown instances of possessing powers that make red glowing symbols float around him.
- Spatial Warping: Alastor is able to get around with the help of his shadow. This was first shown when he teleports behind Charlie and Vaggie after entering the hotel for the first time.
- Portal Creation: Alastor can get around easily as well as transport others easily via the portals he makes. This is shown when he pulls Niffty out of a fireplace he summons.
- Voodoo Magic: Alastor clenches his fist until droplets of blood can be seen as a means to defeat Sir Pentious.
- Pyrokinesis: Alastor summons a ball of fire to distract Charlie as he shoves Vaggie away before starting his reprise.
- Manifestation: Alastor summons both Niffty and Husk out of nowhere and makes cheap booze appear for Husk.
- Photokinesis: During his introduction, he is shown to be able to project red glowing light from his eyes as well as his microphone.
- Outfit Alteration: Alastor is capable of changing the outfits of his targets as well as his own with a snap of a finger without having to do it manually.
- Alastor's name can be translated from ancient Greek to "spirit of revenge" or "tormentor".
- Alastor, alongside Angel Dust, is the hardest to write for Vivziepop because she doesn’t know all the details of the period of time where they come from and since they are based on some complex emotions she has had in her life.
- Alastor and Angel are also two of the first characters Vivzie has ever created and are two of her personal favorites.
- Vivzie created Alastor way back when she was in middle school.
- Alastor possesses a Transatlantic (sometimes called a Mid-Atlantic) accent, which was common for American newscasters in the 1920's as it was a combination of a regular American accent and the Received Pronunciation (Queen's English) accent used by the British Broadcasting Corporation in their "World Service" radio news.
- Alastor's microphone is a living part of him.
- Alastor and Charlie can sing really well.
- It was once stated that Alastor lived as a deer who was shot and killed by a deer hunter. However, this information has been retconned. Despite this, Alastor still shares similar traits with deer.
- The red markings on the soles of his shoes resemble deer tracks, he has antlers, and two tufts of his hair strongly resemble deer ears.
- When asked if Alastor has a deer tail, Vivziepop said that she doesn't know and decided to leave it ambiguous. Due to the fact that his suit's tailcoat flairs outward mid-torso might hint at the fact he does have a tail and doesn't want or like it compressed under his clothing.
- Viv once mentioned that when she first made Alastor when he used to be a deer, he was afraid of dogs. When asked whether or not Alastor is afraid of dogs, Vivziepop stated that she doesn't think he's afraid of dogs anymore, but still dislikes them.
- She also mentioned that Alastor doesn't like dogs because of backstory reasons she can't reveal. Viv did confirm, however, that it does have to do with how he died, and he doesn't like the way he died.
- When asked what his powers are, Vivzie stated that Alastor's powers are lots of things that she can't say, even she doesn't know all of his powers since he's a secret. However, Alastor is a character that keeps many abilities hidden since he likes to be unpredictable. Because of this, he would sometimes feign the inability to do something that he can actually do for a couple of reasons.
- He can be seen using Voodoo magic as a means to defeat Sir Pentious.
- Alastor dislikes being touched, but ironically can't seem to respect other people's personal space and grabs Charlie, Vaggie, and Husk numerous times.
- Alastor is mixed ethnicity-wise.
- According to Faustisse, he is part Creole.
- Alastor can speak some French.
- According to Vivziepop, Alastor was a big theater person. He would love horror, artsy, slow, and/or creepy imagery movies, as well as dry comedy.
- His favorite song is/would be "You're Never Fully Dressed Without a Smile" from Annie.
- Alastor can play the piano, furby organ (which he owns), violin, trumpet, and saxophone.
- His hobbies are playing instruments every so often, cooking, and pulling pranks on others.
- When asked how he kills people, Vivzie stated that she probably can't reveal that yet. Furthermore, Alastor is not the kind of killer that follows or chases people. This is because he has a strange ethical code against doing it.
- Alastor is a big foodie and enjoys cooking. Though according to Viv, she doesn't think that Alastor is a big fan of sweet things. Instead, he likes bitter and salty things such as meat.
- At MomoCon 2019, when asked if Alastor is going to appear in most episodes, Vivziepop stated that he is definitely a part of the main cast. She feels like there's going to be times where he's not around, but he will show up a satisfying amount and is a big source of conflict.
- Alastor is not a fan of modern technology and doesn't like using any technology that was invented after he died.
- Alastor won't kill a child but will discipline or scare one if they annoy him too much. If he was to see an abandoned baby, he would most likely care for it until it has a mind of its own. He also won't take responsibility if the child accidentally injures itself when he lets them play.
- His casual remark of "so many orphans" during the pilot suggests that he might enjoy seeing children suffer. This could also be in reference to all the beings in Hell having lost their souls, morally and spiritually orphaned.
- According to Faustisse, he is canonically an aromantic asexual but that should not be a reason for shippers to be discouraged and stop shipping him with anyone as long as it's not hurting anyone, per Vivzie's words.
- As evident in The Pilot, Alastor appears to be a total mama's boy which Faustisse also confirmed.
- Alastor, alongside Charlie and her mom, are fans of pineapple on pizza.
- Alastor is the only Sinner-turned-Demon that does not have a nickname in Hell. Instead, he sticks with his true name since he is not a fan of making nicknames for himself.
- Alastor is a food snob and hates food like canned cheese, green/purple ketchup, Easy Mac, etc. 
- Alastor may be ambidextrous, as the pilot shows he can be seen snapping and handling his cane with ease using either hand.
- Alastor wears gloves.
- He doesn't take care of his nails, so he doesn't want people noticing that.
- This could also be due to his aversion to touch in which he wears gloves not to soil himself with other demons.
- Alastor has black gums. 
- Alastor seems to steal Husk's drinks for himself at times. 
|Main characters||Hazbin Hotel||Angel Dust • Alastor • Charlie • Husk • Niffty • Vaggie|
|Helluva Boss||Blitzo • Millie • Moxxie • Loona • Stolas|
|Overlords||Alastor • Lilith • Lucifer • Rosie • Valentino • Velvet • Vox|
|Supporting characters||Baxter • Cherri Bomb • Crymini • Egg Bois • Exterminators • Helsa • Katie Killjoy • Mimzy • Razzle and Dazzle • Seviathan von Eldritch • Sir Pentious • Tom Trench • Travis|
|Others||Arackniss • Barbie Wire • Collin • Eddie • Fat Nuggets • Henroin • Loo-Loo Land Mascot • Molly • Octavia • Roo • Robo Fizz • Tilla • Villa|