Cosmic beings are no longer too far from the eager fans of Marvel and superhero comics in general. Since its early days as Timely Comics, Marvel has created a plethora of characters, many of which hail from outer space, often playing key roles in various story arcs.
Some cosmic beings in Marvel have diverse and complex origins, frequently appearing alongside well-known characters to propel the evolution of storylines. Meanwhile, other entities tend to be supporting characters, appearing sporadically in certain narratives. Regardless of their roles, these beings have always been a fertile ground for Marvel to create some of the most unique species in their comic universe.
Kronans

First appearing during the Silver Age, Thor did not initially engage in battles against notorious cosmic entities or supervillains. Instead, the god of thunder faced off against an alien race known as the Kronans. With their defining characteristic being their rocky, durable skin, dubbed “the beings from Planet Krona,” the Kronans played a minor role during the Silver Age but have since evolved into a significant cosmic race in the modern era of the Marvel universe.
One prominent Kronan is Korg, who made appearances in several Marvel Studios films. Korg was a member of Hulk’s Warbound during the Planet Hulk events. This character showcases that Kronans are indeed a formidable species, especially when it comes to their innate resilience. Moreover, their reproductive abilities are quite unique, as they can merge with each other in a lava-like stream until a new entity emerges.
The Brood

Chris Claremont’s classic X-Men series drew significant inspiration from the Alien film franchise. Not only did he incorporate themes from Alien’s Xenomorphs, but he also created the Brood, an alien race that shares a similar parasitic reproductive trait. The Brood implants its eggs directly into living hosts.
What’s particularly horrifying about the Brood is that upon hatching, they immediately begin to assume the physical characteristics of their host. Much like the Xenomorphs, the Brood operates under a hive mentality. They are notably intelligent and adept at utilizing their innate psychic abilities to transform their host bodies into formidable warriors.
Dire Wraiths

Marvel possesses many cosmic beings with shapeshifting abilities, among which the Dire Wraiths stand out. Lesser known than the Skrulls, Dire Wraiths are characterized as “evil incarnate” and their motives are rarely benevolent. Unlike the Skrulls, who have various motives and often act based on established rules, the Dire Wraiths are depicted as malevolent entities devoid of any noble intentions.
Dire Wraiths can assume the identities of other life forms by siphoning the essence of their hosts through a process known as “psychic vampirism.” They often operate based on scientific principles and utilize shapeshifting abilities to maintain a constant state of stealth. The Dire Wraiths’ home realm is similarly dark, often residing in an eerie dimension called Limbo.
Flora Colossi

Groot is one of the most famous characters in Marvel, gaining immense popularity after appearing in the Guardians of the Galaxy films by Marvel Studios. Groot is a member of the species known as the Flora Colossi, a highly intelligent plant-based race originating from Planet X. They possess the unique ability to communicate through a single phrase: “I am Groot,” which has been conveyed numerous times throughout the MCU.
However, Groot stands out uniquely as he serves as a guardian for the Maintenance Mammals, a species with the ability to sustain life on Planet X. The Flora Colossi are known for their strong environmental preservation instincts and exhibit remarkable adaptability.
Cotati

Flora Colossi are not the only plant-based species in Marvel. The Cotati serve as another example of this race, originating from a group of sentient plants who have been forced to share their home planet with the Kree. Due to the continuous pursuit and persecution by the Kree, the Cotati have evolved to lose their ability to move freely, becoming a species that communicates through telepathy.
This telepathic ability allows them to maintain close communication with one another and with other species. This power has enabled them to assist Mantis in becoming the Celestial Madonna, ultimately leading to the birth of their offspring, Sequoia, who later became a leader among Cotati during a campaign to eradicate all life forms in the universe.
The Technarchy

In addition to the various alien and plant species, Marvel has also created several techno-organic races. One of the prominent ones is the Technarchy, an alien race with the ability to shapeshift, always seeking to develop in limitless ways. Similar to the Brood, the Technarchy also thrives on a host organism through the use of the Transmode Virus.
When a being becomes infected with this virus, its body will begin to transform into intricate techno-organic forms that can be absorbed by the Technarchy. The most notable member of this race is Warlock from the New Mutants, who has managed to escape the evil grasp of the Technarchy to become a superhero in his own right.
The Phalanx

The Phalanx is another type of techno-organic entity. However, unlike the Technarchy, the Phalanx has a hive mind, allowing them to access a repository of knowledge accumulated over thousands of years and enhancing their own consciousness within the cosmos. The Phalanx also serves as a formidable combat force, constantly seeking ways to expand their influence throughout the universe.
When the Phalanx land on a planet, they will try to assimilate the local populations and organisms present on that world. If the planet is unsuitable, they will systematically infect it with a techno-organic virus to initiate Technarchy-like transformations and ultimately destroy it. The Phalanx created the Technarchy as a means to wipe out life in the cosmos.
Symbiotes

Symbiotes are a well-known alien race in the Marvel comic universe. First appearing as the black suit of Spider-Man, they later “came to life” as Venom. However, symbiotes are essentially parasitic organisms that embody various emotions and collective traits.
Created by Knull, a dark god with ambitions to transform living beings into monstrous parasites, the significant traits of symbiotes have led to the emergence of various alien species that adopt their traits, including concepts of identity and love. Rather than creating a unique culture, symbiotes absorb the essence, traits, and characteristics of their hosts, adapting them to their own needs.
This allows a symbiote to be profoundly influenced by its host. They can become extremely malevolent if bonded with a villain or, conversely, could serve as a superhero when the host is a hero with a strong moral compass.
The Watchers

While not a race of alien beings like many others, the Watchers are considered one of the most powerful entities in Marvel. Originating as a single being with the ability to manipulate technology, the Watchers have since become a collective responsible for observing the universe without interference in its events.
Uatu is one of the most notable Watchers, residing in the Blue Area of the Moon to observe Earth. With immense power, the Watchers can manipulate matter around them as well as their own forms to carry out any purpose they wish. However, some individuals have occasionally broken their oath to intervene in significant events in human history, as depicted in Marvel Studios’ animated series What If…?
Druffs

Unlike many other cosmic beings in Marvel, Druffs are not very intelligent and are often portrayed as somewhat inept. These small creatures have an almost childish mentality, resembling very young plants. Druffs also have a unique reproductive ability, as one infected Druff can create three entirely new ones.
Druffs typically appear as a background element in the narratives of more intelligent species. One notable example involves the Skrull Emperor Dorrek attempting to assassinate Quicksilver and Scarlet Witch by exploiting the involuntary reproductive abilities of the Druffs to incapacitate these two superheroes.
Source: Marvel, CBR