Developed by the Terran Hegemony in the 25th century, the Mackie was the first true BattleMech. Based on advanced technology that the Hegemony Armed Forces (HAF) had been developing for decades under Director-General Jacob Cameron, the Mackie was the ultimate manifestation of Hegemony military might. The Mackie’s first combat trial was on February 5, 2439, outside of Yakima, Terra. The pilot, Colonel Charles Kincaid, utterly obliterated his test targets, four remote-control Merkava heavy tanks.
When the Mackie was first built, it epitomized the Terran Hegemony's technological advantage over the great houses. It was the pinnacle of military technology until 2455, when the plans were stolen by agents of the Lyran Commonwealth. Still, the Mackie had such symbolic importance to the Terran Hegemony that it remained in production until the start of the Amaris Civil War, although it has not been built since then.

It has four variants:
•MSK-5S
•MSK-7A
•MSK-8B
•MSK-9H
And also a Hero Mech:
•MSH-9HKR - Mackie Kill Roy's Little Buddy
The unofficial mascot of the Desert Wars portion of the Martial Olympiad, Kill Roy uses two LB 10-X autocannons instead of the single AC/20. Two tons of ammunition are stored in each side torso. For protection the torsos are equipped with CASE. To make room for these, the Beagle Active Probe has been removed. Thirteen Double Heat Sinks keep the 'Mech running.