Janeway used a nano virusthe Borg were years behind comprehending to wipe them, out. She infected herself, and allowed herself to be assimilated. Faking hiding using stealth tech she knew wasn't effective against the Borg.
However, the Queen captures the admiral and begins to assimilate her into the Borg collective. Admiral Janeway then turns the tables by unleashing a pathogen she was carrying in her bloodstream into the collective, devastating it and killing the Queen.
Picard killed the Borg Queen after she tried to persuade Lieutenant Commander Data to give her the encryption code by which he had locked the Enterprise's computer.
In one of the few instances of the Borg negotiating, in exchange for safe passage through Borg space, the Voyager crew devises a way to destroy the otherwise invulnerable Species 8472. A Borg drone, Seven of Nine, is dispatched to Voyager to facilitate this arrangement.
Towards the end of the year 2377, the USS Voyager under the command of Captain Kathryn Janeway, with the aid of Admiral Kathryn Janeway from the future, destroyed the Borg Collective's Transwarp Hub and also infected Unimatrix One with a virus that killed the Borg Queen and severely damaged the Unicomplex.
Summary. Admiral Janeway cameo considered for Picard Season 3, but showrunner Terry Matalas feared it would overshadow Seven of Nine's story. Seven of Nine's journey in Picard Season 3 was one of the best story arcs, starting as First Officer and ending as Captain of the Enterprise-G.
Species 8472 possessed superior bio-technology to the Borg Collective, and used it to swiftly destroy multiple Borg Cubes. Species 8472 launched their own invasion of Borg space, something that Janeway believed to be a major threat to the future of the Delta Quadrant.
The Borg quickly realize that Species 8472 is immune to assimilation and that contemporary Borg technology is no match for it. In fact, 8472 is one of the few species so advanced that its ships are able to destroy Borg cubes in seconds.
The Borg learn everything they know about an enemy through assimilating beings. The Borg couldn't assimilate Species 8472 because their immune systems were hyper-advanced.
However, it is widely credited to have been primarily created by Maurice Hurley. The concept of the Borg was first introduced in the second season episode "Q Who?" which aired in 1989.
During a brief moment of contact, Janeway helps them destroy the Borg cube, with all hands on board. Although Seven manages to escape, Janeway is killed. Her memorial service sees a vast turnout, and a tall gleaming pillar with a light burning atop it is constructed in tribute to her.
The role, of course, went to Genevieve Bujold, who departed soon after production commenced. Voyager's producers again called back Gibney, though Kate Mulgrew ultimately won the role.
Subsequently, in the Pocket TNG novel Before Dishonor, Admiral Janeway was assimilated by the Borg and became a Queen who was eventually defeated by Seven of Nine. In the Star Trek: Destiny trilogy, a newly installed Queen oversaw a massive Borg invasion of the Alpha Quadrant.
However, a Hirogen can be seen during mind meld scenes in "Infinite Regress", indicating that Seven of Nine herself, or at least the Borg as a species, already had assimilated Hirogen before Seven's liberation from the Collective.
After the original Borg Queen (Annie Wersching) helped Picard and his motley crew travel back in time, she assimilated Jurati. The Borg Queen and Agnes merged into a hybrid Queen and formed a new kind of Borg Collective to protect the United Federation of Planets.
The Borg would become an unstoppable force, able to assimilate or simply change the galaxy to fulfill their vision of perfection. In addition to gaining all the knowledge of a particular Q, having their consciousness uploaded to the Borg collective, they would also potentially gain the god-like power of a Q.
Officially, the existence of a Borg homeworld is a hypothetical one as it has yet to be revealed in a canon Star Trek source. However, an identity for the Borg homeworld is given by the non-canon novel Lost Souls, which names it Arehaz.
Species 8472: Also known as the Undine, they were a highly advanced and biologically unique species from fluidic space. Due to their vastly different biology, the Borg were unable to assimilate or adapt to them.
However Geordi said that Data was able to move faster than Borg drones, who couldn't move any faster than a human; while Data could move fairly quickly over almost any terrain (but he couldn't swim at that time).
The borg collective as a whole didn't join the federation it was just a small splinter group of the borg that joined the federation the main borg collective is still an enemy of the federation and would mostly likely never join the federation instead would keep on trying to assimilate the federation.
Although any further details would be purely speculative, it fits with the established canon and timeline that the ancient Romulans could've started experimenting with artificial life forms, accidentally created the Borg and realized the terror their experiments had given rise to.
While Picard was ultimately able to defeat them, the Borg were still considered a lethal threat throughout the galaxy. That changed significantly with the events of Star Trek: Voyager's final episode "Endgame," which set the stage for Picard's final showdown with his greatest enemy over two decades later.
On stardate 50984.3 the Borg faced their destruction after they invaded Species 8472's fluidic space with intent to assimilate this species. Unfortunately – for the Borg – Species 8472 DNA encoding was so dense that nanoprobes could not assimilate their cells. Species 8472 responded with an all out attack on the Borg.
