Marvel Studios is featuring a specific group of villains in X-Men '97 Season 2 that were never included or referenced in any of Fox's X-Men films, making their appearance in the upcoming season of the Disney+ show fairly historic. The X-Men have actually been featured on-screen quite a bit throughout the years, most notably in Fox's X-Men franchise, which included more than a handful of flicks. Across those movies, some of the most popular X-Men villains were showcased, but since the X-Men have been so popular in the comics for decades now, the movies literally couldn't include all of the team's major villains.
Marvel Animation recently released a brand new TV spot for X-Men '97 Season 2 that lasted exactly one minute, and within the trailer, it was confirmed that the Brood will be featured at some point in the upcoming installment. For reference, the Brood was not showcased in any of Fox's X-Men movies and has never even been included in any live-action Marvel project.
Specifically, one of the creatures from the Brood race can be seen in a blink-and-you'll-miss-it moment at the 0:52 mark in the TV spot. Wolverine, with a ripped costume and his claws pushed out, is seemingly jumping at a Brood individual in the midst of a fight.
The footage doesn't leave much to the imagination and essentially spoils that part of the action as Wolverine successfully decapitates the Brood, resulting in a splash of green blood all over the shot.
While there are many creatures and insectoid races throughout the Marvel universe (especially in the comics), the thing featured in the X-Men '97 footage is undoubtedly a Brood. The creatures can be somewhat easily identified, as they look like insects, but do not share a lot of the same characteristics as normal insects.
For starters, the Brood are massive in body size. They also have fangs instead of pincers, like a lot of insects. It is also worth noting that they have triangular-like pieces of flesh/exoskeleton that protrude out of the top of their head. The creatures also have tentacles for front legs, as well as stingers, so they are extremely dangerous.
Another great way to get a picture of what the Brood look like in the comics is to compare them to the Acklay from the Star Wars universe. Of course, they aren't exactly the same, but there are quite a few similarities.
It seems as though Marvel Animation tried to stay as faithful as possible to the Brood's original design from the comics as possible, as there are very few differences between how they look in the source material and in X-Men '97 Season 2 (which critics are saying is near-perfect).
The full TV spot for X-Men '97 Season 2 that features the Brood can be seen below:
Why Are the Brood Not In Other Marvel Projects?
The Brood are more of a deep cut when it comes to the Marvel universe as a whole. They have been featured in tons of comic book storylines, but have never really been brought over into anything on-screen.
It is worth mentioning that X-Men: The Animated Series (which is X-Men '97's predecessor) did include a group of insectoid creatures called the Colony during its run. The Colony was obviously heavily inspired by the Brood, and was essentially Marvel including the Brood in that show in everything but name.
The only other TV or movie projects the Brood has been in have been animated titles, and their roles in those have been nothing more than extremely easy-to-miss cameos. However, the Brood has been featured in multiple video games.
Due to the popularity of the X-Men and how popular some of their main villains (such as Magneto, Apocalypse, Sabretooth, Cassandra Nova, Mr. Sinister, the Sentinels, etc.) are, it just wouldn't make a lot of sense and wouldn't be as compelling for the Brood to be the main villains of an X-Men movie. Most likely, that was Fox's exact thought when making all of its X-Men films, if the Brood even crossed the creative team's mind at all.
However, it is interesting that X-Men '97 will be bringing them to life on Disney+. It is possible that, if they are handled well, they could return as minor villains in a future season of the show, or even as a minor antagonist in the MCU when the X-Men movies in that franchise are released.