When the Kree want to take over a planet, they start by establishing a scientific base there. You know, because you might want to experiment on the genetics of the populace. It's not always worth keeping the base fully staffed while they wait for the experiment to finish, so they just leave a Sentry robot there to monitor the situation and protect things.
So basically, think of it as a Sentinel, but for aliens instead of mutants.
The Kree Sentry bot is built from six pieces - there are seven figures in this Captain Marvel movie series, but one of them doesn't have a BAF part, and thus doesn't count for our current purposes. Get all the pieces (either by buying the figures yourself, or from someone who did) and you can plug together a big space robot of your own! Have it ineffectually defend your private spaces!
The original Kree Sentry, Sentry-459, first appeared in Fantastic Four #64, meaning it was designed by Jack Kirby.
This toy isn't a perfect copy of the art seen in the comics, but wow, does it ever carry that design proudly! It's more of an "influenced by" than anything else, but the parallels aren't hard to find: the lines on the shoulders, the harness on the chest, the way the armor comes down from the hips onto the legs... those may not have been things Kirby drew, but they're absolutely inspired by things that were. They've just all been pushed further, to make the Sentry look more mechanical while still retaining the quintessential "robot in a wrestling singlet" look.
The top of the Sentry's head looks like a Moe Howard bowl cut,
which is kind of silly, but not incorrect. The eyes are large black pods with blue evergy crackling across them, and instead of a mouth, that part of the face is covered by an angular plate that wraps around the cheeks. Kirby drew the mouthal area more like the face mask on a football helmet - a couple parallel bars - but this works, too. The Sentry's "clothes" are dark purple while his "skin" is a pale, silvery blue, meaning the eye-zaps are the only bright color to be found.
The addembled figure stands over 8¼" tall, which is honestly probably too short. Maybe. Kree Sentries range in size from 6' to 30', and most of them share the same basic design, so this is acceptable. The most famous one, Sentry-459, was about 15' tall, but there was no way we were going to get a 15" Build-A-Figure in this day and age. The figure moves at the head, neck, biceps, elbows, wrists, chest, hips, thighs, knees, and ankles, and the huge feet will keep it standing in many a pose! Having the thigh armor extend down over the joint makes it look more natural, too. Several of the joints were very stiff - the biceps, for instance, I couldn't get moving at all until the arms were plugged into the torso and it could provide some extra leverage there.
I was really planning the cherry-pick this series; the comic-based figures were nice enough, but I wasn't really jazzed for Captain Marvel (a situation not helped by the first trailers making it look like the most generic superhero movie imaginable). And yet, here we are with a review, proving that I did in fact end up getting all the figures. So I guess the Kree Sentry BAF successfully did its job after all - that's more than you can say for any of the ones that have appeared in the comics, huh?
Nick Fury | Talos | Captain Marvel | Yon-Rogg | Grey Gargoyle | Genis-Vell