Arrow 5×08 “Invasion!” also marks the show’s 100th episode. Star Stephen Amell marks the occasion with some poignant words.

Amell took to Facebook to share his thoughts on Arrow reaching 100 episodes:

Amell says he “can’t believe our 100th episode is airing tonight. Because of the network we’re on, and the long shadows cast by The Vampire Diaries (RIP, Brady The Werewolf) and Supernatural (RIP, Background Character I Eventually Play Who Is Brutally Murdered) people might be inclined to think that 100 episodes come along easily. They don’t.”

Amell notes that to reach a milestone like 100 episode, “You have to be incredibly fortunate. More importantly, you have to be surrounded by a singularly talented Crew and Cast. Directors and Writers. Executives, Network and Studio Heads. We are. We really, really are.”

He also notes the special circumstances surrounding Arrow‘s 100th episode celebration: “We also have the incredibly unique and — possibly — unprecedented opportunity to celebrate this episode alongside three other shows that have helped populate this television universe into something magical. A four night crossover! Aliens?!?! What a treat.”

Amell goes on to particularly thank Katie Cassidy (Laurel Lance), Jamey Sheridan (Robert Queen) and Susanna Thompson (Moira Queen) for appearing in the episode: “Katie Cassidy coming back to play an integral role in our episode while filming a movie in Boston is a testament to her work ethic and her integrity both personally and professionally.” He calls her “magnificent” and says “it was so much fun to run it back with her.”

He adds that “Jamey Sheridan threw himself into the experience.” He explains that “being familiar with a character you haven’t really played in four years in a workspace where everyone has such a familiarity is no simple task.” Sheridan, Amell enthuses, “made it look easy.

And he gushes over Susanna Thompson, noting, “When we lost Moira Queen the show lost a little bit of its soul.” He says the 100th episode “would’ve been incomplete, and maybe even impossible to execute without the warmth she brings to every minute she spends on set.” Her return was a “kind gesture.”

Finally, Amell goes on to thank “[t]he fans, from all over world, young and old… whether you discovered Green Arrow in the 1940’s or you discovered the show somewhere between October 10, 2012 and tonight, thank you.”

He reflects, “This experience has fundamentally altered the lives of more people than you can possibly imagine. What a ride. And as the caretaker of such a beloved character and the representative of such a rich history, I have always tried my very best to keep you entertained. I will continue to do so.”

He closes, “Here’s to another 100 episodes.”

EP Marc Guggenheim explains the concept of the 100th episode, “Invasion!”: After Oliver, Sara, Thea, Diggle and Ray were abducted by the Dominators at the end of The Flash episode, “These five characters are essentially being held in stasis by the Dominators. To keep their minds occupied, they’re in what we call a shared hallucination.”

“The memory flashes that all the five characters experience, that gave us a lot of opportunity to revisit footage from the previous 99 episodes,” Guggenheim explains.

As for any regrets Guggenheim might have over the first 100 episodes of Arrow‘s run, Guggenheim admits, “Doing 23 episodes a year, you’re just constantly running, so nothing ever turns out exactly the way you want it to. In other words, my list of regrets is actually incredibly long; it’s 100 episodes long.”

As for his biggest regret? “I wish we had allowed the Oliver-Felicity storyline in season 4 to unfold at a more natural pace. We had set these tentpoles at the beginning of the season, and we were a bit too rigorous on how we hit them. That was a case where the planning overtook the storytelling. We didn’t do things as naturally and as elegantly as we should have.”

What are your favorite ‘Arrow’ moments in the first 100 episodes?