In most Transformers continuities, "Optimus Prime" is the name of the Autobot leader, but that's not the case in Transformers Animated. Early on, it was revealed that "Prime" is a rank, and that Optimus isn't the only one.
Graduate of the same class as Optimus Prime at the Autobot Academy, Sentinel Prime is commander of a squad of the best the Autobots have to offer - the Elite Guard. Though he is a powerful warrior and a cunning leader, he is also obsessed with following rules to the absolute letter. He is unbending in his interpretation of procedure, and dislikes the way Optimus Prime and his crew improvise. If he had his way, that whole group would be sent back to Basic Programming.
"Sentinel Prime" is one of those names that Transformers loves to reuse for each new incarnation, but this is the first time he's ever shown up on a cartoon and, more importantly, had a toy. Heck, in most versions of the story, it was his death that saw Optronix promoted to Optimus Prime, so there's generally a good reason why he's a plastic vigrin.
This figure depicts Sentinel Prime in his Earth mode, a snowplow. The truck is 5⅜ long,
counting the plow, and has the sort of giant tires favored by douchebags. This is actually Sentinel's idea of a "typical Earth vehicle" that "won't attract attention." Yep, nothing less out-of-place than a truck with a plow on the front, driving down the street on a sunny day. And not only that, judging by the side-by-side comparison seen in the show, this is supposed to be a monster truck, bigger than Optimus Prime's semi-truck cab! Yeesh.
are easy enough to follow, and don't leave anything out. There is one unintentional feature, though, that's just a function of the engineering necessary to get him to change modes: like a real snowplow, Prime's shovel can be adjusted to point left, right or center. It's a small addition, but realistic.
When considering Sentinel Prime's robot mode, it's important to remember that his design was completed
only after his voice actor was cast. Why does that matter? Because said actor is Townsend Coleman, a name which probably doesn't mean anything to you. It'll help if you know he's most recognizable as the voice of The Tick on Fox's much-loved '90s cartoon. Spoon! Since they knew he was going to be the voice of Sentinel, a lot of the Tick was brought in to not only the design (he's blue, he's strong, he has antennae and a huge chin even by TFA standards), but also the characterization (he's dumb) and even the dialogue (he says lots of silly things without realizing it).
Articulation is very good,
with a balljointed head and hips, swivel/peg shoulders, hinged elbows, swivel thighs and hinged knees. That's more than enough to leap from rooftop to rooftop, to fight Dinosaur Neil or to wield the included weapons: a lance and a shield. While both are energy-based on the cartoon, they're unexpectedly not cast from translucent plastic for the toy. Kind of strange, that. The two pieces can hook together to be stored inconspicuously on his truck mode.
The character who eventually became Sentinel Prime was originally going to be named "Rodimus Prime," another familiar old name. Apparently Hasbro didn't like the notion of Rodimus being a huge jerk (as opposed to just being hugely unpopular, like he usually is), so the name was changed, allowing Sentinel Prime to break new ground. Of course, it may be a good thing: if he was Rodimus, he probably wouldn't have been allowed to be blue, and we would have lost some of that Tick-y goodness!