win.gg
Win.gg News Who is Sans? How Undertale’s secret boss became an indie icon

Who is Sans? How Undertale’s secret boss became an indie icon

Author Icon
William Davis Published 09/03/2022

Despite playing only a small role in Undertale, Sans is now one of the most famous characters in all of gaming. 

From his iconic theme song to his unmistakable voice tone, it seems that gamers just can’t escape from Sans. Undertale’s most fascinating support character is a constant fixture throughout the game, offering advice and warnings to the player. His mysterious nature and laid-back attitude make him a core part of almost every Undertale fan theory. For fans of the series who want a refresher or players just now picking up Undertale and Deltarune, here’s everything there is to know about Sans.

Undertale’s most iconic character Sans is surpsingly humble

Sans is one of many supporting cast members in Undertale. He appears at various points throughout the game to guide the player or to warn them about the consequences of their actions. Sans wears an iconic blue hoodie and black athletic shorts. While his eyes are usually pitch black, one of them can glow blue under certain circumstances. Sans does not play a clear role in the underground monster society. 

He and Papyrus are brothers, and Sans will strongly react to the way that the player interacts with Papyrus. Sans appears in almost every major area before or after key events. His exact role varies depending on the game route that player chooses. In pacifist and neutral runs, Sans will act as a supporting character. In genocide runs, Sans switches to a primary antagonist who attempts to stop the player at multiple points, either by force or through appealing to their emotions.

How to fight Sans in Undertale

Sans’ boss fight in Undertale is locked to the very end of a genocide run, and it’s by far the most difficult battle in the entire game.

While normally a friendly face, Sans becomes a direct antagonist to the player in the genocide run of Undertale. This playthrough requires the player to kill every single monster they see, including random overworld encounters. All named characters like Toriel, Papyrus, Undyne, and more must be defeated in their story battles. A number of other tasks must also be completed in order to fight Sans in Undertale.

Sans will meet the player in the final corridor just after Asgore. He will confront the player and threaten them before initiating the battle. The following fight is extremely difficult and has several gimmicks. Instead of dealing damage in chunks, Sans deals just one damage several times per second that slowly ticks down the player’s health. His health pool is very large and the fight challenges the player’s endurance. 

Players who defeat Sans are immediately leveled up to the level cap, which is useless since he is the final fight of the game. His dialogue will also change depending on if the player has previously defeated him.

What is Sans lore in Undertale?

Sans’ lore is that he is the only underground monster aware of the player character’s powers. He acknowledges the power of determination as a way to reset time back and forth. It is implied that, while Sans has awareness of the ability, he is unable to use it himself. This doesn’t really matter in the pacifist and neutral runs of the game, but it has a significant effect on the genocide route.

When Sans challenges the player at the end of a genocide run, he does so knowing that no matter how many times he wins, the player can always reset time and try again. 

Sans is also loosely connected to another mysterious Undertale character, W. D. Gaster. Their exact relationship is not known, but Sans owns a hidden machine that appears to be made by Gaster and uses weapons internally called “gasterblasters.” This lack of information has made Sans a frequent subject of Undertale fan theories and content.

William Davis
About William Davis

View full profile
Read Also
Twitch CEO says AI can assist streamers, not replace them News
Twitch CEO says AI can assist streamers, not replace them Conn Mc Gillion Twitch CEO Dan Clancy believes that livestreaming remains more human-focused in the age of artificial intelligence. Speaking at the Fortune Brainstorm Tech conference in Aspen, he said: "AI is trying to take humans out of the equation, and live is one of the formats that keeps humans at the centre. You connect with people. You can understand them. You can see who they are." The comments came during a discussion ...
What is Twitch’s Creator Sponsorship Certification, and how can it help small streamers? Twitch
What is Twitch’s Creator Sponsorship Certification, and how can it help small streamers? Khizar Mundia Twitch's Creator Sponsorship Certification is expanding, and it has the potential to help smaller streamers get off the ground when it comes to partnerships. Sponsorships are an essential part of many streamers’ career, as they provide a steady and potentially lucrative income for broadcasting sponsored content. While there is no guaranteed method for a streamer to get signed by a brand, Twitch has a course that could be beneficial. Twitch's ...
Thrill announces new Original Roulette — here is how it plays Slots
Thrill announces new Original Roulette — here is how it plays Fariha Bhatti Thrill has made another addition to its stacked range of Originals, with the crypto casino announcing the release of Roulette. The classic table game rounds off the list with timeless mechanics and a distinctly modern twist. Thrill is a leading crypto casino and hosts a vast library of online slots and games that appeal to players of all tastes. From mainstream heavyweights like Hacksaw Gaming to underrated studios like Endorphina, ...
Roshtein hits huge Graffiti Ways win after losing day Big Wins
Roshtein hits huge Graffiti Ways win after losing day Fariha Bhatti Roshtein’s most recent win on Graffiti Ways came out of nowhere, leaving the streamer $4.8 million richer. Graffiti Ways comes from Colorful Play, a software provider that launched in 2025 and exists only within the Stake ecosystem. The slot is set in a graffiti-sprayed alley, and is known for its vibrant symbols and a five-scatter hidden bonus, a combination that turned it into an instant streamer favorite on release and ...
Nina Lin arrested and banned on Twitch following New York Knicks celebrations Twitch
Nina Lin arrested and banned on Twitch following New York Knicks celebrations Fariha Bhatti New York Knicks championship celebrations turned sour for streamer Nina Lin after the NYPD arrested her for climbing on top of a moving Amazon delivery van. Nina Lin has become synonymous with controversy on Twitch, so you'd think a recent ban would become her cue to lay low. Instead, she's back in the spotlight, and this time she's gone too far. The streamer spent the night of June 13 in ...
MrBeast reaches 500 Million subscribers amid claims of $24 million in YouTube revenue Twitch
MrBeast reaches 500 Million subscribers amid claims of $24 million in YouTube revenue Khizar Mundia Jimmy “MrBeast” Donaldson is one of the most popular content creators in the world. The YouTube star recently surpassed 500 million subscribers, and an alleged leak of his creator dashboard appears to reveal the platform revenue generated by his channels. MrBeast started small, but his ambition and drive helped him transform viral challenges and philanthropic stunts into some of YouTube's most ambitious productions. That success recently culminated in him becoming ...
Pokimane comments on Sykkuno’s comeback as xQc weighs in Twitch
Pokimane comments on Sykkuno’s comeback as xQc weighs in Khizar Mundia Sykkuno's return to streaming after a roughly two-month hiatus prompted criticism from Imane "Pokimane" Anys, sparking another beef between her and Felix "xQc" Lengyel. Pokimane and xQc have clashed publicly on several occasions, with their latest disagreement centering on Sykkuno. After Pokimane criticized the streamer and voiced support for those affected by the controversy, xQc pushed back, arguing that the situation was being mischaracterized. The situation has even seen Sykkuno ...