Arrow star Stephen Amell is a busy man. Between filming the Arrow season 3 and The Flash finales and getting ready to shoot for Teenage Mutant Ninja Turtles 2, Amell clearly has a lot going on. But that didn't stop the actor from engaging in a little Q&A at the Vancouver FanExpo held over the weekend.

Apart from comparing Casey Jones (the fan-favourite character he will play in the next Turtles film) to Oliver Queen, Amell revealed some interesting details on the much-talked about spin-off series, due to debut next year.

This planned spinoff show will bring together characters from the Arrow and The Flash world and introduce new ones. The show will feature The Atom, Firestorm, Rip Hunter, Hawkgirl and more.

"I would imagine that I will be appearing on all three shows," said Amell during the panel at Fan Expo Canada. "I would imagine that we will be sprinkling characters in. I know that there's a plan for one character who originated on Arrow and is not one of the main characters on the new spinoff to sort of hover between all three shows and that will be their job, so to speak. So you'll see a lot of interconnectivity next year."

Who could this mysterious character be? "Given her friendships with the key characters on all three shows, Emily Bett Rickards' Felicity Smoak could be a safe bet," speculates ComicBookMovie. Check out Amell's FanExpo video below:

Meanwhile, another Arrow star David Ramsey, who plays John Diggle, has revealed that the sinister organisation H.I.V.E. that features on Arrow a couple of times, will be the main antagonist in season 4.

"From my understanding, H.I.V.E. is going to be a big part of next season's big baddie. We are going to delve right into why H.I.V.E. hired Deadshot to kill Andy and what H.I.V.E. is all about to begin with. There will be a lot of Diggle's connection to H.I.V.E.," Ramsey told E! Online.

The new episode of Arrow season 3, titled Broken Arrow airs on 15 April on The CW.