8. Malcolm Merlyn
I feel like this might be cheating, but after actually seeing John Barrowman in person and hearing him talk about his time as Malcolm Merlyn, there was no way he couldn’t be in the top 10. Perhaps the only reason he didn’t end up higher in the rankings is that after the first season, the character didn’t quite develop as strongly as he did in season one.
Just looking at season one, and Malcolm is one of the greatest villains to grace our screen in the Arrowverse. His motivations are based on emotions and make perfect sense, helping to propel his story forward in a way that absolutely worked to make the series brilliant.
With the help of the brilliance that is Barrowman, Malcolm Merlyn was one of the most engaging characters across all of the Arrowverse. And after his death at the end of the first season, it only made sense that they wanted to keep him on, even if that required the use of flashbacks and other devices.
I think where he lost some steam however is that in later seasons, his motivations are less clear and it doesn’t always make sense when he is either attacking Team Arrow or doing his part to help them out. But no matter what happened in those later seasons, Malcolm Merlyn was still one of the greats and that’s why he has to be a part of the top 10 of Arrow characters.