- Beam Me Up, Scotty!: Her absence in Crisis on Earth-X was purely because of artistic reasons; the writers decided not to feature her in the crossover. It wasn't because Katie had to attend her father's funeral. In fact, David Cassidy died after filming wrapped up.
- Creator Backlash: She was as unimpressed as the fans were when Laurel was killed off in the Season 4 of Arrow, claiming that she still wanted to star in the show. Fortunately, she returned the same year to star as her character's doppelganger in The Flash and eventually transferred back to Arrow.
- Dye Hard: Katie is a natural brunette, but her best-known roles are blondes. Zigzagged in Arrow; Laurel Lance was a brunette when she first appeared, but wore a blonde wig upon taking her superhero mantle of Black Canary and later dyed her hair blonde. Her Evil Doppelgänger was likewise a brunette when she first appeared but dyed it blonde while impersonating her original counterpart.
- Dyeing for Your Art: She lost a significant amount of weight during the production of Arrow Season 2, to better convey Laurel's addictions to painkillers and alcohol. The following season, she bulked up in the gym as Laurel suited up as Black Canary.
- Enforced Method Acting: In Arrow's fourth season, she apparently trained with Caity Lotz (her on-screen sister and Canary predecessor) occasionally, likely to establish their characters as a Sibling Team in future episodes.
- Reality Subtext: In Arrow, she played a character who has an alcoholic father. Her real life father also has alcohol problems.
- Star-Making Role: Supernatural got her attention, but she really became a household name when she starred as Laurel Lance in Arrow.
- Those Two Actors:
- Has appeared with Leighton Meester on both Gossip Girl and Monte Carlo.
- Has appeared with Willa Holland on both Gossip Girl and Arrow.
- Oddly, she and Stephen Amell both guested on New Girl in its first season on separate occasions, shortly before their stint on Arrow.
- Has appeared with Debby Ryan in two independent films in 2018, Cover versions and Grace.
- Typecasting: Her debut film appearance in When a Stranger Calls started her career as a Scream Queen of mostly forgettable horror films in the late 2000s/early 2010s. Her television roles in contrast are more diverse. Thanks to Arrow, she is mostly known today for her superhero role, rather than being a Scream Queen.
Trivia / Katie Cassidy