5. All the DC TV shows are connected

Arrow, The Flash and Legends Of Tomorrow work not only because of The CW‘s willingness to embrace its many comic book superheroes but because they are all connected. Felicity can pop over the help the team in Star Labs, Cisco built the latest version of the Arrow-cave and even the titular heroes can team up, from small cameos like those seen at the end of the last season to the full-blown two-part annual crossover event that has been a hit with fans everywhere.

We’ve already had the arrival of John Constantine, played again by Matt Ryan in early Arrow season four, which means his short-lived NBC show Constantine exists in the same universe. With Barry Allen now popping over to National City, so too is Supergirl. It might take the multiverse to do it, but now there is that possibility of seeing Supergirl – or even Superman – help out our heroes in Central and Star City.