Zelena (Once Upon a Time)
In December 2013, Rebecca Mader was cast as the Wicked Witch of the West. She made multiple appearances during the second half of season three and was promoted to a series regular for the show's fifth season. The role of the Wicked Witch of the West was written specifically for Rebecca Mader. It was announced that the writers had chosen not to continue with Zelena's storyline and Mader would not be returning for the seventh season of the show. However, Mader later revealed that she would be returning for multiple season seven episodes.
Ruby Slippers (Once Upon a Time)
The Oz events take place years after the flashback scenes from "Our Decay", they also take place immediately after Zelena is banished to Oz in "Swan Song" and before she goes back to Storybrooke in the present day scenes in "Our Decay". The Oz present events take place not long after Zelena leaves. The Underworld events take place after "Her Handsome Hero"