Guardian

Guardians are Megatron's elite bodyguards. Although, they have no alternate modes, they can shift into three different forms: Patrol, Investigate, and Battle.

Transformers: Fall of Cybertron
The Guardians patrolled the Decepticon-controlled ruins in the Sea of Rust under the orders of Shockwave in anticipation of Autobot snoopers. Autobot snoopers did arrive in the form of Cliffjumper and Jazz. While the Guardians' sensors proved capable to see through Cliffjumper's cloaking ability, the Autobot's skill allowed him to sneak up and defeat the Guardians with ease.

Guardians were also employed in Shockwave's security towers, and engaged the similarly cloak-equipped Starscream in combat.