Gosamyr first appeared in New Mutants #66 (August 1988), and was created by Louise Simonson and Bret Blevins.
She subsequently featured in The New Mutants #67-74 (September 1988-April 1989); Power Pack #42 (December 1988); X-Terminators #4 (January 1989); and The Mutant Misadventures of Cloak and Dagger #4 (April 1989). During this time Simonson said she was considering having Gosamyr reform and join the New Mutants, depending on how much Simonson liked her. However, Gosamyr was written out of the series with The New Mutants #74.
Gosamyr received an entry in the Official Handbook of the Marvel Universe Update '89 #3.
Gosamyr is a member of an ancient, but rare, race of alien beings. In line with her heritage, Gosamyr is a very beautiful and delicate humanoid creature in her early stage. Once they reach adulthood, members of her race cocoon themselves for several thousand years before finally emerging as large powerful monstrosities. If released too early they can be powerful enough to destroy planets, even solar systems. The female of the species also has empathic powers which, even without intent, can cause conflict between even the closest of friends to the point of destruction. Provoking such conflict has evolved into the cultural norm for the species as a means of vying for dominance. As part of this, Gosamyr used her beauty to seduce male humans. She even tries to chat up eight-year-old Jack Power, who resents her approaches.
Through some bad business dealings by her brother, Gosamyr and her family are forfeited to the evil alien businessman Spyder. Spyder keeps most of Gosamyr's family imprisoned while she herself is kept at the end of a leash as a pet.
Through similar arrangements, Spyder had also acquired "property rights" over Lila Cheney. Lila is kidnapped by Spyder's men in spite of the efforts of her friends from the New Mutants. While in Earth's orbit, Gosamyr gives Spyder the slip, steals a space yacht and goes to Earth to find the New Mutants and ask for their help to save both her family and Lila.
Gosamyr and the New Mutants follow Spyder to a planet where greed and the search for profit is the norm. On their space voyage, Gosamyr manipulates the New Mutants and causes conflict between them in order to establish herself as the alpha female of the group. Only Warlock, being a Technarch, is immune to her manipulations and suspects that Gosamyr is a threat before it is too late, and her manipulations have exposed Rahne's repressed feelings for Lila's boyfriend Cannonball, caused Magik to lose control of her demonic essence, and brought the New Mutants to blows with each other. Magik breaks the spell by striking Gosamyr with her Soulsword. Now with Gosamyr as their prisoner, the New Mutants break into Spyder's palace to rescue Lila, but are captured by Spyder, who has been monitoring their progress and using Gosamyr's nature to lead them into a trap.
Gosamyr frees the New Mutants by using a trick which makes her invisible. They then discover that Gosamyr's family are in their cocoon stage and Spyder intends to force them out and kill them to use their bodies to make valuable textiles. Exiting their cocoons long before their time, the creatures grow with every passing minute and threaten to destroy the planet and its solar system. To prevent this, Lila apparently teleports them and herself into the sun. Now orphaned, Gosamyr nonetheless accepts that Lila's killing her family was necessary.
Magik then uses her own teleportation powers to get the New Mutants and Gosamyr away from the planet and into Limbo, only to find themselves trapped there. Gosamyr remains on the fringes, using her emphatic power to keep the demons away from her. She no longer actively manipulates her companions, and though Warlock remains suspicious of her, New Mutants co-leader Mirage has forgiven her earlier misdeeds.
Gosamyr helps out clearing the damage after a demonic invasion of Manhattan. She uses her powers to help relieve the pain of male patients in a local hospital. More controversially, she helps the kids from Power Pack reconcile with their parents who, in the course of fighting an enemy, discovered that their children had super-powers which they had kept secret from them. The parents suffered a nervous breakdown as a result, but Gosamyr convinces them that their children are still normal. (This "cover-up" was highly criticized in the readers' letters column.)
Gosamyr and her companions decide to take up residence in the spacecraft Ship, the ally and mobile headquarters of X-Factor. However, upon scanning Gosamyr, Ship recognizes her species and tries to kill her. Though the New Mutants fight Ship to a standstill in her defense, the incident convinces Gosamyr that her nature makes her too much of a danger to the New Mutants and their friends. Ship informs her of a planet of mystics who might be able to teach her to curb her nature and provides her with a spacecraft with which to go there. Resolved to not cause any more harm to her friends, Gosamyr takes Ship's suggestion and leaves Earth.
While in the larval stage, Gosamyr possesses wings that allow her to glide over short distances. She can also become invisible once she wraps herself in them. She also possesses some empathic control over the male species, which she mostly uses to seduce or bring about conflict.
The pupal stage of Gosamyr's species lasts for millennia, during which they become exceptionally mature of spirit and gain great size and strength, enough to destroy a whole solar system. However, in adult form they are gentle and solitary.