IN PHOTO: Cast Member Grant Gustin Attends A Panel For The CW Television Series 'The Flash.'
IN PHOTO: Cast member Grant Gustin attends a panel for The CW television series "The Flash" during the Television Critics Association Cable Summer Press Tour in Beverly Hills, California July 18, 2014. MARIO ANZUONI/Reuters

"The Flash" pilot episode airs Tuesday, Oct. 7 on The CW. It is a bigger judgment day for "Glee" alum Grant Gustin, whose casting alone was already subjected to a lot of criticism. Some DC comics fans argued Gustin looked too young to play Barry Allen. Spoilers reported by those who have seen the show sound promising, though.

Despite a lukewarm reception to news of his new role, Grant Gustin drew positive reviews when he was first seen as Barry Allen in a 2-parter special on Arrow. In the said superhero series, Barry bonds with Arrow's Felicity Smoak, played by Emily Bett Rickards. The Flash premiere spoilers reveal Stephen Amell, who plays Oliver Queen/The Arrow, is making a special appearance.

The Flash Season 1, Episode 1 is called, "City of Heroes." For those who were unable to see Barry Allen get struck by lightning, watch The CW's Arrow Season 2, Episodes 8 and 9.

The outlook is good for The Flash premiere, if one would consider the 19 million views that this Flash video (trailer) has drawn so far. (Watch the full trailer of The Flash here or scroll down to play the video.)

ABC's "Marvel's Agents of S.H.I.E.L.D." was compared to The CW's "The Tomorrow People" a year ago. That battle was won by SHIELD, which is now in its sophomore run. (TTP has been cancelled, and its lead Robbie Amell has been cast as Firestorm in The Flash.) Now it's The Flash versus Gotham by FOX. Who wins this round between the two new superhero shows?

Joining Barry Allen in The Flash premiere episode are: Dr. Harrison Wells (Tom Cavanagh), Detective Joe West (Jesse L. Martin), Dr. Caitlin Snow (Danielle Panabaker), Iris (Candice Patton), and Cisco Ramon (Carlos Valdes).

John Wesley Shipp, who is The Flash of the 90s on TV, will be introduced as Barry's beloved dad in The Flash Season 1, Episode 1.

Here is a list of "10 Things To Know" about The Flash, from the makers of The CW's Arrow (also actively endorsed by Stephen Amell in his social media channels).

WATCH: The Flash Pilot Episode Airs On The CW, Extended Trailer Goes Viral On YouTube

The Flash airs Tuesdays on The CW. Its trailblazer, Arrow (also based on DC Comics universe), airs Wednesdays.