Star Wars: Everything We Know About George Lucas' Sequel Trilogy
8. Darth Talon
A popular Legends figure who appeared many, many years after the Battle of Yavin in the Expanded Universe stories, Darth Talon was a female Twi'lek who became a Sith Lord and seduced a direct Skywalker descendant to the Dark Side, and looked set to be involved in Lucas' trilogy.
Lucas was a fan of the character, and while it's not 100% that she would've been in his final version of the movie, she did appear in storyboards and concept art that emerged back in 2013, when the first artwork for the movie was starting to surface, suggesting she would have played a role in at least Episode VII.
Pablo Hidalgo, part of Lucasfilm's Story Group, wrote in a since-deleted tweet that "The Jedi Killer morphed from Talon corrupting the son to becoming the son," meaning that whatever role she had was seemingly amalgamated with that of Ben Solo.