Cal-141

"Take the shot, O'Brian, now! You're the only one who can do it!"

- Cal ordering O'Brian to kill the Prophet.

Cal-141 was a female SPARTAN-II Commando of the UNSC Naval Special Warfare Command.

Assassination Attempt
During an operation to assassinate a Minor-Prophet on a Covenant-held planet, Cal-141 commanded a group of four Orbital Drop Shock Troopers, consisting of a young Dutch, O'Brian, Cortez and Checkman. Though three remained after the drop as Checkman was killed in the upper atmosphere of the planet insertion. During the operation, Cal fights a Brute Chieftain that wielded a Gravity Hammer and seemed to have been winning the fight, while O'Brian hung for dear life over a waterfall, though Cal rescues him soon after.

Death
While waiting for the Prophet to arrive, the Brute Chieftain that Cal had supposedly killed the day before was still alive and ambushes Cal and the three ODSTs. Cal spots the Chieftain about to strike O'Brian and quickly moves to get the ODST sniper out of harm's way, but she is hit across the head and right shoulder by the Chieftain's Gravity Hammer, no doubt resulting in fatal injuries despite her armor taking the blow. It is when the Chieftain was dead by being shot in the head repeatedly by Dutch that Cal's helmet is removed by Cortez that it is revealed that Cal is a female, as opposed to the squad believing she was a male, stunning the trio completely, especially O'Brian and Cortez.

After O'Brian killed the Prophet, the ODSTs tried to tend to Cal's wounds, but she knew that she was not going to make it back to the Destroyer. In her dying words, Cal asked for Cortez to make a delivery to Dr. Halsey. This delivery consisted of an optical chip from Cal's helmet. This chip contained intelligence of the planet the mission was carried out on, as well as ruins that were neither human or Covenant. Cortez tried to assure her that she would be able to give the chip to Halsey herself, but Cal replied that the two of them knew it was not going to happen as she felt her death already moments away. She held Cortez's hands a bit longer and eventually died before the three ODSTs.

Cal's death left a profound impact on the ODSTs with whom she fought with on the mission. They, like all ODSTs had a bitter rivalry with the Spartans and considered them to be freaks, but Cal's efforts in the mission and her actions in saving O'Brian's life many times until the loss of her own, they had changed their thoughts and opinions on the Spartans. This change was shown well as the ODST team later returned to their ship, where both Cortez and Dutch angrily scolded a marine for mocking Cal's combat credentials, and O'Brian pondered on how he might be dead if it hadn't been for her.

Publicly, she was likely classified as MIA as opposed to KIA, as per ONI policy regarding the deaths of the supposedly-invincible SPARTAN-II supersoldiers.

Trivia

 * She is one of the main characters of The Babysitter, a story focused on a UNSC mission to assassinate a Covenant leader, and the feud between the SPARTAN-II Project and the Orbital Drop Shock Troopers. It is one of seven short films of the anime adaptation Halo Legends.
 * Cal's hair is significantly longer than the regulation length allowed for the UNSC military.