According to TVLine, Arrow Season 6 will be welcoming back Charlotte Ross as Donna Smoak, mother of Felicity Smoak (played by Emily Bett Rickards). The character was originally introduced in Season 3 and has not been seen since the finale of Season 4, where she left town after nearly being killed by Damien Darhk.
Though the details of the character’s return have not yet been revealed, she has logged enough narrative and screen time with both Felicity and Quentin Lance (the two were romantically involved throughout the show’s fourth season) to make a natural return.
It is still unknown which Season 6 episode will mark the character’s return.
Arrow airs Thursdays at 9pm on The CW.