Sentinel Prime personified what a leader should be: wise, compassionate, and a more than worthy warrior. Revered by both Autobot and Decepticon, few would dare stand against his shield and Primax Blade.
While Sentinel was presumably lost forever on board the Ark, Optimus Prime, his hand-picked successor, was left to fill his void. The loss of Sentinel signaled the end of Cybertron's golden age, and the planet spiraled deeper into war.
Some who recall Sentinel's reign bitterly remember when Transformers were masters of their fate, rather than scattered to the stars and living as exiles. Above all, Sentinel Prime is a staunch nationalist. He loves his home planet with all of his Spark and will do anything- even go to extremes- to protect it.