Cortana is one of the Halo series' biggest characters, second only to Master Chief himself. Appearing in the vast majority of all Halo media, not just the games, she has become so important that she is literally Microsoft's version of Siri.

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Despite all the fame and popularity, a lot of the details about this character remain a mystery, even to a decent portion of Halo fans. This is why we've put together some things that every person who has played Halo should know about everyone's favorite AI.

10 Based On Catherine Halsey

Starting off this list with something that most fans probably know about Cortana. While it isn't said a lot in the games, Cortana is actually based off of the mother of the Spartan program Catherine Halsey. Cortana was made using a copied version of Dr.Halsey's brain, 20 flash copies were made but only two survived, with one of those two becoming Cortana. The other brain was also used to create an AI, that AI being name Kalmiya, which is considered to be Cortana's older sister.

9 Other Influences

While Cortana was based on Catherine Halsey and is considered to be a clone of her, she has other influences as well.  There are some influences that exist in Cortana based on Halsey's daughter Miranda Keyes but in the creation of Miranda for Halo: Combat Evolved, the character took influences. Cortana's face was model after a sculpture of the Egyptian Queen Nefertiti while the rest of the body she chooses to appear as appears as a younger version of Dr.Halsey.

8 Name References

Cortana's name is a reference to a previous game made by Bungie and a historical figure. The name Cortana is a variation of the word Curtana the sword used by the Ogier the Dane who was one of the 12 knights of Charlemagne. This continues a trend that Bungie had going on at the time of naming thins after swords. Specifically in one of their previous games Marathon 2: Durandal where the subtitle is a reference to the Durendal sword used by Roland, another Knight of Charlemagne.

7 First Words

Cortana was first activated on Reach and her first words were "Quando il gioco è finito, il re e il pedone vanno nella stessa scatola." This phrase is in Italian and when translated to English they read "When the game is over, the king and the pawn go in the same box."

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These are the words that were spoken to Dr. Halsey by her mother after Catherine beat her in their first chess match together. After saying that Halsey's mother proceeded to beat her for winning.

6 Birthday Reference

Cortana's date of birth, more officially known as the day that her service began was November 7, 2549. The more keen-eyed and clever members of Halo's fan base might have noticed that this isn't just some random date in the Halo timeline. At first one might think to the events of Halo: Reach but that's not what we are talking about. No this date when you look at it, November 7th, is actually 11/7 like John 117. Yup her birthday is a reference to her soon to be partner.

5 Voice Actress

In most Halo media, at least in English, Cortana is voiced by veteran video game voice actress Jen Taylor. Jen Taylor is also well known for being the voice of gaming's first lady, Princess Peach, despite not actually being a gamer herself. Taylor has provided the voice of Cortana for every Halo game, as well as the voice of Halsey to solidify the connection between the two.

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The only time that Taylor has not voiced Cortana was in the Halo Anthology series Halo: Legends.

4 Original Accent

In the original drafts of Halo: Combat Evolved, Cortana was going to have an accent similar to a British isle one. This was an idea that must have been changed later in the development of the game as in the search for voice actors for the character, they were specifically looking for one's who could do a convincing British accent. This was later dropped but Cortana still uses some British Island and phrases when she talks like "Sod Off!" when she's talking to Guilty Spark.

3 Easter Eggs

A large portion of Halo 3's plot is based around Master Chief's search for Cortana. This is bolstered by Chief having visions of her, as well as the various bread crumbs that she leaves so that Chief and Arbiter can actually find here. These tapes and flashbacks aren't the only times we see Cortana before we actually save her In the game's second last mission, however, if the player accesses a UNSC terminal and watches the bottom left of the screen, they will see Cortana's face pop up for a few seconds before disappearing.

2 How She Survived Halo 4

This is something that is never really explained too well in Halo 5, which is just another part of what people complain about in terms of Halo 5. While the ending of Halo 4 left most people thinking Cortana sacrificed herself it turns out that she was only uploaded to the Domain, which is the collective intelligence of the Forerunners. doing this cured her of her rampancy and deeming her worthy of the Mantle of Responsibility in the eyes of the Warden, causing her to go mad with power.

1 Original Story Of Combat Evolved

Despite what happened to her character in Halo 5, most people still remember Cortana as the funny and helpful AI sidekick to Master Chief and remains a series favorite. This is also bolstered by Cortana now being Microsoft's personal AI assistant for all of their devices. However, this was supposed to be very different. An early draft of Halo: Combat Evolved's story had Cortana as a Mad AI that wants to control the universe that Chief would discover. Maybe the writers took some inspiration from that for Halo 5's story.

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