Despite being one of the most honourable characters in the Marvel Universe, he saved our universe many times in MCU and comics also. It’s important to remember that Stephen Strange wasn’t always a decent person.
When Strange joined the Ancient One’s disciple, he mainly left his basic tendencies behind and embraced his better nature. Nevertheless, there have been instances where readers have seen a peek of Doctor Strange’s dark side in both the Multiverse and the Prime Universe. Doctor Strange is a useful ally for the forces of good, but he also possesses traits that may turn him into one of the evilest in this world or any other. Here’s the list of evil versions of Doctor Strange.
Loki, Sorcerer Supreme

Marvel Comics
After a magic tournament, the Vishanti declare that Loki is the new Sorcerer Supreme, leaving Doctor Strange almost powerless and working as a veternarian.
A mystical competition takes place every few decades. The Vishanti, a trio of godlike beings who serve as the Sorcerer Supreme’s supporters, are hosting the competition between sorcerers. Doctor Strange has easily defeated the other sorcerers for the previous 20 years. He also triumphed over them this time. Unexpectedly, the Vishanti chose to elevate Loki, the God of Mischief, to the rank of Sorcerer Supreme. Doctor Strange objects that Loki didn’t even take part in the competition! However, he is ultimately compelled to give Loki the title. But the Vishanti proclaim Loki to be the new Sorcerer Supreme, rendering Doctor Strange practically helpless and forced to become a doctor.
Loki travels to the Bar with No Doors, a covert establishment frequented by magicians from various realms, with his new title in tow. Due to his reputation for deceit and treachery, the other wizards do not like him. Loki is searching for The Exile of Singhsoon, the most powerful fabled spell. All of the magic in the universe is claimed to be able to be absorbed by the spell, which eventually renders all other people’s abilities useless but for the spellcaster’s own.
Doctor Strangefate

Doctor Strangefate is an amalgam of DC Comics’ Doctor Fate and Marvel Comics’ Doctor Strange and Charles Xavier. Strangefate discovered that the Amalgam reality would be destroyed if the two keys that Access possessed were used to restore the DC Comics and Marvel Comics realms. Dr. Strangefate enlists Skulk and White Witch to kidnap Access and bring him to Strangefate so the Amalgam reality may continue to function in order to preserve his realm. Dr. Strangefate is unable to stop the extinction of his reality since he discovers Access has hid the keys elsewhere.
Later, in the All Access miniseries, it is revealed that Strangefate was able to survive the end of Amalgam by ingratiating himself deeply into Dr. Strange’s mind. He then preserved the whole Amalgam universe in a pocket dimension by manipulating the Sorcerer Supreme.
Leader of the Black Priests

Marvel Comics
To keep the multiverse’s balance, the powerful magic users known as the Black Priests wipe out particular timelines of Earth. The Black Priests serve noble goals, unlike Galactus. In the long run, the sacrifices they make are beneficial. Thor and his friends encounter a horde of Black Priests in New Avengers #27. Thor finds out shortly after that Doctor Strange has taken over as the Priests’ new commander. Strange possesses the ability to mould reality to be anything he desires because he is a member of the Black Priests.
Strange can speak in complete words, unlike the other Black Priests. He is now far more potent than the other Black Priests as a result. To equal Strange’s skill, other Priests must cooperate as they can only speak with the sound of a single letter.
Doctor Strange Supreme

Disney+
This version of Doctor Strange is shown in the first season of the Marvel animated series What If…? first appearing as the subject of the fourth episode. It can be considered the evilest version of Doctor Strange.
In an other Earth-199999, Doctor Strange loses his girlfriend Christine Palmer in a car accident, but instead of losing his hands, he becomes a Master of the Mystic Arts. Despite his initial heroism, Strange eventually turned to the dark side after losing his love, absorbing numerous interdimensional creatures to gain the strength to change the past and bring her back to life. The darker Strange is warned by The Ancient One and another Doctor Strange incarnation that establishing such a paradox would bring the universe to an end, but their warnings ultimately went unheeded.
The universe is obliterated in front of them as a result of Strange’s successful alteration of destiny and the resurrection of Christine Palmer. As soon as Strange realises he’ll lose Palmer to the end of the world once more, he starts to display repentance and begs The Watcher to step in.