The original licence to create Marvel Comics Action Figures was obtained by Toybiz in 1990, with the first figures released in 1993. In 1998 Toybiz merged with Marvel Entertainment to create Marvel Enterprises, and continued to produce Marvel 6 inch Action Figures under the Legends banner. In 2006, due to the bankruptcy of Marvel Enterprises the master licence for Marvel figures was purchased by Hasbro.
Hasbro continued to produce the Marvel 6 inch action figures, also called Legends, while the Marvel Cinematic Universe movies from 2008 (Iron-Man) - saw Hasbro produce 6 inch figures from each movie on their own card back outside of the Legends stable. In 2014 the Marvel Cinematic Universe action figures were brought into the Marvel Legends line with the subtitle "Infinite Series". The first MCU figures under the Legends banner would be from Captain America Winter Soldier, soon followed by Guardians of the Galaxy.
Hasbro's Legends wave are released as a combination of comic book and movie figures, and within each figure of the wave was a part that could be built into a larger figure - this build-a-figure (BAF) allowed Hasbro to release larger scale figures and the first MCU release of these would be the fantastic Groot from Guardians of the Galaxy.
In 2018, to celebrate the 10th year of Marvel Cinematic Movies, the Legends banner expanded out to produce a series of sets revisiting movies from the past 10-years to give us new and updated characters. This concept was expanded in 2019 to a series of comic book and MCU figure sets to celebrate the 80th anniversary of Marvel Comics.