The 55th Mechanized Brigade was a unit of clone troopers commissioned in 32 BBY, alongside the rest of the Grand Army of the Republic. The unit was deployed in 22 BBY, alongside the rest of the GAR. The unit survived throughout the Clone Wars, between 22 BBY and 19 BBY. A lieutenant within the unit had been injured, which led to him being reassigned to serve at a Republic Detention Center on Pols Anaxes.
In 19 BBY, near the end of the Clone Wars, he assisted a group of individuals in a "prisoner transfer". However, unbeknownst to him was the fact that the group consisted of Bardan Jusik, ex-Republic Commando Fi Skirata, and former ARC troopers Spar and Sull were the individuals there rescuing Ruusan Skirata, the daughter of Kal Skirata, who was the adoptive father of many clone troopers in the Special Operations Brigade, including Fi.
- Unidentified clone trooper lieutenant
- Order 66: A Republic Commando Novel