J. McKenzie
Corporal J. McKenzie was a MACO soldier assigned to  during its mission in the Delphic Expanse in 2153.

Prior to serving aboard Enterprise, McKenzie conducted a six-week tour on Jupiter Station, where the periodic failure of the artificial gravity led her to gain a proficiency at operating in gravity boots. ()

McKenzie accompanied Captain Archer and Lieutenant Reed to investigate a derelict alien vessel which the Enterprise crew had encountered in the Orassin distortion field. Later, she was part of the boarding party which was transported to the Osaarian base inside a Delphic Expanse sphere. () Upon his death in 2154, McKenzie's commanding officer, Major Hayes, recommended that Reed utilize and rely upon McKenzie due to her familiarity with the MACO team. ()

As of 2154, she and Travis Mayweather had exactly one conversation following a training session. ()

Alternate timeline 
In an alternate timeline in which Enterprise was thrown back in time from 2154 to 2037, McKenzie developed a romantic relationship with Mayweather, and the two eventually married. After learning of it in the ship's database, he shared this detail with Hoshi Sato, who asked how close he and McKenzie had been prior to the displacement. Upon hearing that they'd only talked once, she then suggested he ask her out. This timeline was eventually negated when, with the help of the descendants of their temporally-displaced counterparts, the Enterprise crew managed to avoid the accident which had thrown them back in time in the first place. ()

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Humans
MACO personnel
Enterprise (NX-01) personnel