Evil Shirley is an alternate version of Shirley Bennett, the product of a divergent timeline in which the study group suffered great personal losses. Shirley herself was heavily traumatized by witnessing the death of Pierce Hawthorne as she was sprayed with his blood and fell off the wagon, becoming an alcoholic. Devastated by those tragedies, the Abed of that reality dubbed this The Darkest Timeline, and suggested they become as dark and twisted as the reality they had to endure. Shirley was largely indifferent to his plans although she accepted one of the felt goatees he passed out as a symbol of the group's new evil purpose. It's assumed that she later agreed to take part in the plan when Evil Jeff declares after Evil Annie's trial that he and the rest of the "Evil study group" plot to destroy the "Prime timeline". Her first appearance was in the Season Three episode "Remedial Chaos Theory". She is portrayed by Yvette Nicole Brown.
In the study group's second year at Greendale, Shirley and the rest of the group decided to celebrate Troy's 21st birthday at a bar. When Shirley learns that at the last minute the plans changed and everyone was to meet up at an establishment called Ballroom, she panics. While they were there, Shirley tried desperately to hide the fact that she use to patronize that bar. She threatened the bouncer, who recognized her immediately, and also tried to collect all the photos in the bar that had her in it. However, she missed one that was in the restroom, which was found by Britta. Along with Jeff and Troy, Britta made fun of Shirley's past drinking problem which was evident in the photos. Humiliated, Shirley explained that she frequented the bar during a "dark time" in her life (presumably, this happened after her husband Andre left her). She expressed anger at the trio for mocking her past mistakes and left the bar in a huff.
In the study group's third year at Greendale, Troy and Abed decided to move in to an apartment together. A housewarming party was thrown where the roll of a Yahtzee die determined who would go downstairs to grab the pizza from the delivery guy. Six different scenarios unfolded that split off from the "Prime Timeline", one which ended up becoming The Darkest Timeline. In that alternate reality, a chain of events led to Shirley being sprayed with Pierce's blood after he was shot accidentally by Annie's gun. She was so disturbed by the event that she turned to drinking again to cope. When the group met afterwards in the study room, Britta expressed her concern to Shirley about her drinking saying she had enough. Shirley simply replied she had enough of Britta. The Abed of that timeline suggested an outrageous plan; they would all commit to becoming "evil" by wearing felt goatees, cross over to the "Prime Timeline" and take over their counterparts' lives. Shirley was far too inebriated to seriously consider Abed's plan and put the felt goatee on a beer bottle she was drinking out of ("Remedial Chaos Theory").