Is the term "Dark Jedi" oxymoronic?

Question

I thought I had an original thought; luckily Google proved otherwise. I thought the term "Dark Jedi" seemed oxymoronic, because if you fall to the Dark Side, you're going against the Jedi Order, hence you wouldn't be a Jedi anymore, right? I found this discussion where another person had the same idea, but this user stated:

There is no way a Jedi can be "dark", because the Jedi are selfless. The words "Jedi" and "Dark" can not be used to describe the same person, since they represent opposite values. ...That would be like someone who believed in the teachings of Jesus but worships Satan - It makes no sense.

That got me thinking instead, "If that's the case, to fit the term 'Dark Jedi' a Jedi would have to still believe in the Jedi Code, and intentionally break it."

Wouldn't that person be even more evil than a Sith? I mean, the Sith follow a doctrine. In this case a "Dark Jedi" would purposefully do things against his own doctrine with the intent of just being purely evil, whereas Sith are doing what they think is best, at least.

So is there any level of canon where there are any Jedi that would actually fit this definition of a "Dark Jedi" - one who believes in the Jedi Code, but intentionally goes against it? Not bending the rules, Qui-Gon-style, but staying as a Jedi and undermining the Jedi Doctrine?

Answer 1

Legends Canon

The term 'Dark Jedi' first appeared in the original Thrawn Trilogy by Timothy Zahn (which is now 'Legends' canon):

• Heir to the Empire

• Dark Force Rising

• The Last Command

Zahn had to come up with a label for a Jedi who had fallen to the dark side, and the term Sith would not be properly defined for another few years. He went for "Dark Jedi," which he himself regarded as "descriptive if not very original." With time, the definition of the term became progressively less precise, and Dark Jedi ended up referring to both fallen Jedi and malevolent Force-users who never underwent proper training.

https://starwars.fandom.com/wiki/Dark_Jedi/Legends

Additionally, in terms of "official" Disney canon, Wookieepedia says:

In the official Star Wars canon, the term Dark Jedi was first used in the "Classic Moment" article of Star Wars Insider 155, which was published in January 2015. The article featured Asajj Ventress and her duel with Ahsoka Tano and Luminara Unduli aboard Tranquility, referring to Ventress as a Dark Jedi.

https://starwars.fandom.com/wiki/Dark_jedi

Official (Disney) Canon

In terms of actually falling away but not becoming a Sith or being a Force user but not beholden to the Jedi Order - the new canon book 'Dark Disciple' has two examples:

Ventress has abandoned the Sith way but is a bounty hunter and uses her Force skills for profit. She also undertakes a mission to assassinate Dooku on behalf of the Jedi Order who assign Jedi Quinlan Vos to assist. They fall in love and he leaves the Jedi Order to stay with her. Vos embraces the Dark Side to gain more power and assist in the assassination, but does not embrace a Sith way of life. He eventually returns to the Order.

Answer 2

I the term "Dark Jedi" as understood now may be an oxymoron, but the original intention of the term was to describe Jedi who had fallen. The term Sith had not yet been devised. From Wikipedia:

Dark Jedi and the Sith: Dark Jedi is the unofficial name given in the Star Wars universe to antihero fictional characters attuned to the Force and adept in its dark side. The concept of "Dark Jedi" is not endorsed anywhere within the movie trilogies. They exist by that name only in the Star Wars expanded universe, including video games such as Star Wars: Knights of the Old Republic and the Star Wars: Jedi Knight series; the term is never used in any of the six Star Wars films. So called Grey Jedi and Rogue Jedi are terms that refer to Jedi who don't follow the Jedi Code and/or the decisions of the Jedi Council, or who have defected from the Jedi Order and/or have rejected the Jedi Philosophical concepts of "Lightside" versus "Darkside". Fallen Jedi refers to former-Jedi-turned-Sith who were seduced by the Dark Side (such as Revan or Anakin Skywalker).

Definitions: Dark Jedi and Grey Jedi are a label to a specific archetype of characters in the Star Wars Expanded Universe defined as Force-attuned beings that meet two requirements:

They do not hold themselves to the dogma of either the Jedi or the Sith.

They use their Force abilities for less than virtuous pursuits–acts that are normally forbidden by the Jedi Order.

Dark Jedi in the Expanded Universe typically refer to pupils of Luke Skywalker's Jedi Academy who have fallen victim to the dark side. Dark Jedi are also extremely common in the Knights of the Old Republic series in league with the Sith Empire and are often fallen Jedi from the Mandalorian Wars. Dark Jedi also appear in the Jedi Knight series of Star Wars video games, where Kyle Katarn uncovers Imperial plots linked to Dark Jedi. In Jedi Outcast, Katarn faces an entire army of Dark Jedi, cloned and lightly trained force users who follow the main antagonist. Dark Jedi have distanced from Sith in more modern Star Wars media. They are not sworn enemies of the Jedi Order and do not consider destroying it a priority as Sith do. Dark Jedi do not always appear in pairs with a master and apprentice and often work alone.

Because the term Sith was never spoken in the original trilogy (although Darth Vader was described as "Lord of the Sith" in the published screenplay), early Expanded Universe products usually considered the "evil Jedi," those who joined the dark side of the Force, as "Dark Jedi." In his novel series The Thrawn Trilogy, author Timothy Zahn labeled Sith Lord Darth Vader and Emperor Palpatine as Dark Jedi, and the term "Sith" was never mentioned in the series until later reprints of the novels.

So it was basically a generic term used to describe force users who didn't necessarily follow the Jedi or the "Sith" dogmas, and generally used the Force for less than good actions.

As for current Disney Canon

Here is the definition of a "Dark Jedi" from Leland Chee, the official keeper of Star Wars continuity:

A dark Jedi is anyone who practices the dark side of the Force whether or not they were a former Jedi.

from moviepilot.com/posts/3652640

As far as your exact question

So is there any level of canon where there are any Jedi that would actually fit this definition of a "Dark Jedi" - one who believes in the Jedi Code, but intentionally goes against it?

I don't believe there is. There are examples of Sith or Dark Jedi infiltrating the order for various reasons, both personal and in an attempt to bring both the Jedi and the Republic crashing down, but no examples I could find of a Jedi, deciding they no longer wanted to follow the Jedi Code but remaining in the Jedi Order, and now using the dark side of the Force.

As for Quinlan Vos as an example

According to Wookieepedia, (which is still based on Legends canon at this point)

He actually became a member of the Sith when he infiltrated the Jedi Order in an attempt to get his revenge, so he doesn't even technically qualify.

I am not aware of his Disney canon story enough to speak to whether that has changed or not.

Answer 3

In Legends Atris of KotOR 2 had fallen to the Dark Side out of despair, guilt. and fear but remained a Jedi Master through a significant amount of hypocrisy. She still held the Jedi ideals as valuable but was no longer capable of fulfilling them herself, though she pretended otherwise.

In Disney Canon's Rebels cartoon there was significant conflict between Kanan Jarrus and his padawan Ezra Bridger over the latter's willingness to use the dark side to achieve his ends. Ezra Bridger is technically a Jedi as he is the padawan of a Jedi Knight, but the Jedi Order lacks any ability to enforce orthodoxy on him.