Harley Quinn, portrayed by Margot Robbie, is by far the best and most popular character in the DCEU. Without Margot's performance, Harley Quinn wouldn't have the success she has today. With the fallout of a shaky start to the DCEU, Warner Brothers knew they had to run with the only thing that was working, Harley Quinn. Giving Harley her own vehicle in Birds of Prey cemented the fact she is capable of leading a film, but where will Dr. Harleen Quinzel go from here?