Jean-Pierre Delmas, known by students as Mr. Delmas, is the headmaster and principal of Kadic Academy. He is very straightforward, but weak-minded and gullible, and is easily bossed around by his daughter Sissi and easily fooled by the Lyoko Warriors.
Mr. Delmas acts as a stern headmaster at Kadic. He believes that his mission is to mold the children into fine adults, and for this reason he is generally very harsh on them. While he is usually strict on the students especially during season 1, he is shown to care deeply about their safety and well-being. In spite of his aforementioned harshness, he tries to present himself as someone students can go to to talk about their problems and issues.
He often makes announcements to the school via the PA system, as most principals of schools do. Notably, when communicating with Kadic's student body, he will uses the term "children" to address them; ex. "Children, have any of you seen William?", "Children, please give me your attention." (Nicole Weber did this as well in Unchartered Territory). While he believes in following the rules to the letter, he does bend the rules at times, for example allowing Ulrich to accompany Odd to the hospital in Killer Music.
- Jeremie Belpois: Mr. Delmas is very strict on Jeremie as well as all of his students, especially when it involves rule breaking. He is shown to care about his grades (as Jeremie has one of the highest GPAs in the entire school) and questions his motives for occasionally acting up in class, as Jeremie is one of his best students. Mr. Delmas is shown to care about Jeremie's well being, and fired Jim when he accidentally injured Jeremie in Code: Earth.
- Aelita Schaeffer: While not shown very often in the series, it is presumed that Mr. Delmas views Aelita as a good student since she is one of the best students at Kadic besides Jeremie, though he has given her detention on a few occasions.
- Odd Della Robbia: Though rarely shown in episodes, it is implied that Mr. Delmas has frequently interacted with Odd, usually due to Odd getting in trouble. In Saint Valentine's Day, when Odd and Jeremie got each other in trouble by arguing out loud in class about Aelita's mysterious necklace, Mr. Delmas said that Odd wasn't a surprise, meaning he had dealt with him many times before. One notable time they interacted was when Odd tried to convince Mr. Delmas to put him in the same class as his friends in Straight to Heart.
- Yumi Ishiyama: Mr. Delmas' interactions with Yumi have been mostly negative due to their circumstances. The first notable interaction was when he was threatening to call Yumi's parents over X.A.N.A.'s clone of Yumi attacking the school nurse in Image Problem. The second time, he suspended Yumi for a month when she tried to convince him that X.A.N.A. was about to attack the school in Satellite. The third time was in Double Trouble when he threatened to expel Yumi from Kadic Academy if she skipped or was late to class one more time. In Evolution, he and Yumi are shown to talk about the stress of being at school.
- Ulrich Stern: Mr. Delmas appears to dislike Ulrich for multiple reasons. The largest of these reasons is that Ulrich has some of the worst grades in the school, which frustrates his father who then blames him. Also, his daughter, Sissi, has had a crush on him for years, and he would like that drama out of his life. In Nobody in Particular, however, Jean-Piere was easily persuaded to give Ulrich a second chance by Ulrich himself (who was in Jim's body) when he reminded Mrs. Hertz that she was a teenager herself when she wanted to put the aforementioned student in remedial classes.
- William Dunbar: He has been angry with William's clone, due to its stupidity. He also dislikes the real William because he is a rebel. When William’s parents visited Kadic in Down to Earth, Mr. Dunbar, growing suspicious of the fake William, told Mr. Delmas that William was a dynamic and rebellious youngster who was kicked out of his last school for putting stickers all over the school, including on the principal's windshield, which Mr. Delmas then remarked that he was never told this fact when William was being enrolled at Kadic.
- Elizabeth Delmas: Sissi is Mr. Delmas' daughter and the self proclaimed "Queen of Kadic". Mr. Delmas tries his hardest to keep her happy, but this may have caused her to become the selfish girl that she is now. On multiple occasions, Sissi has persuaded (or rather, demanded) her father to hold school dances and other activities for her. But as the headmaster of Kadic, he holds his daughter to a very high standard, even going so far as to not letting her go to the dance for failing the final exam in Final Mix.
- Jim Morales: Mr. Delmas seems to have a slightly negative relationship with Jim. He grew tired of Jim's claims that Jeremie, Yumi, Odd, and Ulrich are hiding something. He even fired Jim when he accidentally caused Jeremie to fall down the stairs, thus breaking his ankle. While Jim is only a gym teacher, Mr. Delmas uses him to do most of the odd jobs around the school, such as fixing machines and keeping night watch.
In Bad Connection, Jean Pierre claimed that he is an electronics buff, and great at fixing phones, but this has yet to be seen considering that he broke Sissi's phone, although it's quite possible that he is not as good as he says he is as he said that his nickname when he was Sissi's age was "Mr. Circuit Breaker" before correcting himself that it was "Mr. Circuit Fixer", to which he accidentally jammed the screwdriver he was using through Sissi's phone.
In the episodes Ultimatum and Wrong Exposure, Jean-Pierre was possessed by X.A.N.A. twice. However, in both episodes, he was possessed without his daughter being possessed with him. He displayed super strength, shooting electricity out of his hands, immunity to cold temperatures, controling his car with his mind, super speed (even on water), and martial arts.
In Ultimatum, he is possessed to kidnap Odd and Yumi as part of an ultimatum. He knocks William aside when he tries to help them, and eventually his actions are reported to the police. Jean-Pierre takes the two into his car and takes them to a refrigerated warehouse, where he is ordered to keep them alive until the ultimatum times up and he is ordered to kill the two. However, Ulrich manages to track them with Jeremie's bomb that was built to stun a person possessed by X.A.N.A., and the bomb works to his advantage, causing Jean-Pierre to be momentarily stunned before regaining consciousness, where he goes to the Factory and fights Ulrich and Sissi. Here, he shows no hesitation in fighting his own daughter, showing that his will was under X.A.N.A.'s complete control. However, after Aelita deactivates the tower, he is released from X.A.N.A.'s possession and the memories of his kidnapping of Odd and Yumi and Sissi learning the secret of Lyoko are erased with a return to the past.
In Wrong Exposure, he was possessed again to kidnap Aelita and deliver her to the Scyphozoa so it could possess her and make her jump into the Digital Sea. He pulls her out of detention with Jim and orders him to keep the others from leaving (but they defeat Jim using their new skills from commando camp) and virtualizes her to the Forest Sector where the Scyphozoa awaits. He then goes back up, and while Jeremie virtualizes Ulrich and Yumi to the Forest Sector, Odd remains behind to fight Jean-Pierre. However, he ends up twisting his ankle, and before Jean-Pierre could kill him, Aelita deactivates the Tower, freeing Delmas, and triggering a return to the past.
- X.A.N.A. Awakens, Part 2
- Seeing is Believing
- Holiday in the Fog
- Cruel Dilemma
- Image Problem
- End of Take
- The Girl of the Dreams
- Swarming Attack
- Just in Time
- Laughing Fit
- Killer Music
- The Robots
- Ghost Channel
- Code: Earth
- False Start
- A Great Day
- Saint Valentine's Day
- Final Mix
- Missing Link
- A Bad Turn
- Cold War
- Tip-Top Shape
- Straight to Heart
- False Lead
- The Pretender
- Temporary Insanity
- Nobody in Particular
- Double Trouble
- Final Round
- William Returns
- Double Take
- Wreck Room
- Opening Act
- Maiden Voyage
- Hot Shower
- A Lack of Goodwill
- A Space Oddity
- Cousins Once Removed
- Wrong Exposure
- Bad Connection
- Down to Earth
Jean is a French variant of the Hebrew name Yehohanan (יְהוֹחָנָן), meaning "God is gracious". Pierre is a French variant of the Greek given name Petros (Πέτρος), which is also the Greek word for stone. Jean-Pierre was an incredibly popular name in France during the late 40s and early 50s, but is now considered old-fashioned, a reference to Mr. Delmas's prim and proper disposition. Delmas is a variant of the French surname Dumas, which means "son of Martin". The name is a reference to Martin of Tours, a Catholic saint and one of the patron saints of France.
- It is unknown what became of his wife, though Sophie Decroisette implied in an interview that he is divorced.
- Jean-Pierre is know to be quite strict with his daughter, although he has implied he is quite generous when it comes to her allowance.
- He is known to play computer games in his office instead of working, as shown in Double Take and Bad Connection.
- In False Lead, Odd named his virtual pet Tamagutchi "Jean-Pierre".
- In the novels, it is revealed that the password of his computer is sissidelmas.
- In Finnish, he was played by Arto Nieminen.
- In the Polish version of the original series, he was played by Paweł Szczesny. In the Polish version of Evolution, he was played by Jarosław Domin.
|Jeremie Belpois | Aelita Schaeffer | Odd Della Robbia | Yumi Ishiyama | Ulrich Stern | William Dunbar|
|Sissi | Jim Morales | Suzanne Hertz | Anthea Schaeffer | Mr. Delmas | Laura Gauthier | Franz Hopper|
|Kiwi | Herb Pichon | Nicholas Poliakoff | Amelia "Milly" Solovieff | Tamiya Diop | Hiroki Ishiyama | Johnny | Takeo and Akiko Ishiyama|
|X.A.N.A. | Monsters|
|Professor Tyron | Ninjas | X.A.N.A. William|
|Jean-Baptiste Pujol | Theo Gauthier | Emily LeDuc | Taelia | Samantha Knight | Samantha Suarez | Heidi Klinger | Mathias Burrel | Magali de Vasseur | Claire Girard | Brynja Heringsdötir | Patrick Belpois | Romain Le Goff|
|X.A.N.A. Aelita | X.A.N.A. Odd | X.A.N.A. Yumi | X.A.N.A. Ulrich | X.A.N.A. Franz Hopper | X.A.N.A. Anthea Schaeffer | Jeremie Clone | Aelita Clone | William Clone | Subdigitals|