With its six seasons and the seventh one upcoming, The Flash is still going strong and is showing no signs of slowing down. It had the time to introduce many intriguing characters. Not only did fans see the main hero, his friends, and sidekicks, but they also saw his family, villains, work colleagues, and many, many more.
Since the show's beginning, Barry Allen was the heart and soul - but even he wouldn't be able to pull it off alone. The Flash is constantly surrounded by people, some which leave a bigger mark on his life while others disappear fairly quickly. However, these are the ones who impacted the story the most...
Candice Patton
Iris West has been with Barry from the start - first as his sister, then as his girlfriend and wife. Iris has changed a lot since the start of the show, but she retained her optimism and good heart. Candice Patton doesn't have that many solo storylines that would put her in the spotlight but she does the best with the space she has.
Teddy Sears
Even though Teddy Sears aka Zoom wasn't the most frightening villain of the show, he still left his mark on The Flash and all its heroes. Sears first posed as a good guy, he lied to the team Flash and said his name was Jay Garrick. He even went as far as to romance Caitlin.
But he had a nefarious plan which he later tried to realize. Sears was believable both as a good guy and a villain, so he belongs among the better villains of The Flash.
Carlos Valdes
Carlos Valdes is one of the less experienced The Flash actors - as Cisco Ramon is his first big major role. But despite that, Valdes does a good job as the resident genius inventor who also was a superhero for the time.
Cisco is just a guy who tries to do the good thing but doesn't always succeed. That, combined with his sense of humor and friendship with Barry and Caitlin, makes him sympathetic to the audience.
Danielle Panabaker
Portraying both Caitlin Snow and Killer Frost is no easy task but Danielle Panabaker pulls it off with grace. However, the show doesn't give her characters as much space as they would have deserved, especially in the last two seasons.
Despite her young age, Caitlin is hiding a lot of pain inside because of the tragedies that befell her. Panabaker shows all of that, as well as Killer Frost's hidden insecurities and the rare moments of happiness for both of them.
Mark Hamill
Mark Hamill is the legend of sci-fi films thanks to his role as Luke Skywalker in the Star Wars franchise. In The Flash, Hamill played the part of James Jesse aka The Trickster, a villain with a penchant for tricks that even the Joker might be envious of.
James Jesse is insane and doesn't have that many layers to him, but Hamill's performance alone makes Trickster one of the most memorable one-time villains.
Matt Letscher
Before the Reverse-Flash got Harrison Wells's face, he looked like Matt Letscher. Just like with multiple actors on this list, Letscher only has limited space on the show - but he makes the most of it.
His Eobard Thawne is frightening in his intensity and his singular desire to bring down his enemy, Barry Allen. Not everybody can convincingly play a villain, but Matt Letscher managed it just fine.
John Wesley Shipp
John Wesley Shipp played the Flash himself in the 90s TV show so it was only natural for him to come to The Flash as Jay Garrick. He also portrayed Barry's dad Henry Allen.
Neither Henry nor Jay Garrick has as much space in the story and it would have been good to see more of them. But anytime Shipp appears on the screen, he easily steals the scene for himself with his charisma.
Jesse L. Martin
Every hero needs a mentor, someone who will advise him when he doesn't know how to go on. Joe West is all that - and more - for Gustin's Barry Allen. Joe West is both a detective and a dad, and combining these two parts of his life is no easy task.
The Broadway veteran Jesse L. Martin exudes calm confidence and kindness in the role, which made him one of the most popular dads in the entire Arrowverse.
Grant Gustin
Grant Gustin has developed a lot as an actor since the first season. Gustin previously portrayed supporting characters, Barry Allen was his first major leading role. Holding an entire show on his shoulders is no easy task but Gustin continues to do it with grace.
His Barry is inherently optimistic at heart but he's been through a lot of ugly things which gives Gustin the chance to express a rich variety of emotions.
Tom Cavanagh
Tom Cavanagh is the one actor who portrayed many different characters in the Arrowverse - even though most of them were various versions of Harrison Wells. Cavanagh has been on The Flash since season one, and in the latest season, he portrayed Nash Well.
However, his best performance is the chilling and intelligent Harrison Wells who later turned out to be the villain Eobard Thawne aka Reverse-Flash.