|Allegiance||US Air Force|
|Out of Stargate universe information|
|Portrayed by||Eric Schneider|
|First appearance||"Children of the Gods"|
Doctor MacKenzie has made himself a specialist in psychology, using with success hypnosis as modern therapeuty (SG1: "Fire and Water"). Part of his work inside SGC involves analysing pychological data from SG units because of the many Stargate travels (SG1: "Legacy").
Soon after Apophis' attack in Stargate Command, Doctor MacKenzie starts to examine the two Serpent guard dead bodies. When Major General Hammond, Major Samuels and Colonel Jack O'Neill come into the infirmary, General Hammond asks Colonel O'Neill if he knew this kind of people. Doctor MacKenzie then states they're not human as they have a pouch inside their belly, similar to a marsupial. He also says they have not made an autopsy yet.
Following Colonel O'Neill, Captain Carter and Teal'c's strange behavior since their return from Oannes, Doctor MacKenzie uses a recorder with specific sounds to increase their level of concentration. O'Neill is upset, but Teal'c reacts when he sees flashes with Daniel Jackson burning in fire among orange bubbles. MacKenzie notices the conflict as all of them state that Daniel is alive and yet Daniel is dead. He tells that both realities can't be true, yet both seem to be.
To solve the issue, MacKenze suggests to use hypnosis to see why three hours and half are missing in their memories and why all of them are conditionned to give specific answers. Carter volunteers. Soon after, using hypnosis, MacKenzie makes Carter retrieving memory of what happened after Daniel's "death".
Doctor MacKenzie reports in the SGC briefing room that Daniel Jackson shows evidences of schizophrenia, may be caused by the Stargate. Because of this report, General Hammond closes Stargate travels. MacKenzie decides to medicate Daniel and let him rest in one of the SGC VIP rooms.
Noticing an increase of schizophrenia, MacKenzie sends Daniel in a mental facility. After Goa'uld killing organisms passed from Daniel to Teal'c, Daniel argues with Dr. MacKenzie to let him go as he's not suffuring anymore. Later, MacKenzie reports to the SGC that Daniel's behavior has changed. After O'Neill's visit to Daniel, MacKenzie frees Daniel from the mental facility.
After Apophis brainwashed Teal'c (SG1: "Enemies"), he's meditating when O'Neill, Dr. MacKenzie and General Hammond come into the secure room. Teal'c seems to have recover and pledges allegiance once more to the Tau'ri. He says that Dr. MacKenzie has convinced him that Apophis is a false god. MacKenzie says that Teal'c convinced himself. General Hammond asks MacKenzie about what he thinks regarding Teal'c resuming duty, and MacKenzie shrugs, letting O'Neill making the decision.
Soon after, Bra'tac meets Teal'c and realizes that Teal'c has deceived all of them.
In the SGC briefing room, Doctor Janet Fraiser reports that Dr. MacKenzie has made a detailed analysis of Daniel Jackson's EEG and MRI reading. According to him, Daniel is in a sort of coma, supressed by other consciousnesses. Daniel seems to carry the minds of at least a dozen of the lifeboat's passengers.
- "MacKenzie" is spelled differently in different episodes. In "Fire and Water" and "Threshold", it is spelled "McKenzie" in English subtitles as well as ending credits. In other episodes, it's spelled "MacKenzie".
- In "Children of the Gods" Eric Schneider (who portrays MacKenzie) is simply credited as "Doctor".