Invasion! (Arrowverse)

"Invasion!"
Arrowverse crossover event
Tetraptych promotional posters for "Invasion!" for (L to R) Supergirl, The Flash, Arrow and Legends of Tomorrow
Also known as	"Heroes v Aliens" "Heroes Unite"
Episode nos.	The Flash (part 1) Season 3, Episode 8 Arrow (part 2) Season 5, Episode 8 Legends of Tomorrow (part 3) Season 2, Episode 7
Directed by	Dermott Downs (Flash) James Bamford (Arrow) Gregory Smith (LoT)
Teleplay by	Aaron Helbing (Flash) Todd Helbing (Flash) Marc Guggenheim (Arrow & LoT) Wendy Mericle (Arrow) Phil Klemmer (LoT)
Story by	Greg Berlanti Andrew Kreisberg (Flash)
Production codes	T27.13108 (Flash) T27.13208 (Arrow) T13.20007 (LoT)
Original air dates	November 29, 2016 (2016-11-29) (Flash) November 30, 2016 (2016-11-30) (Arrow) December 1, 2016 (2016-12-01) (LoT)
Episode chronology
The Flash ← Previous "Killer Frost" Next → "The Present" List of The Flash episodes Arrow ← Previous "Vigilante" Next → "What We Leave Behind" List of Arrow episodes Legends of Tomorrow ← Previous "Outlaw Country" Next → "The Chicago Way" List of Legends of Tomorrow episodes

"Invasion!" is the third annual Arrowverse crossover event, crossing over episodes of the Arrowverse television series The Flash, Arrow and Legends of Tomorrow on The CW, and is inspired by the 1989 comic miniseries Invasion!. Events at the end of the Supergirl episode "Medusa" on November 28, 2016 marked the beginning of the crossover, which officially began on November 29 with The Flash, continued on Arrow on November 30, and concluded on Legends of Tomorrow on December 1. Each of the latter three episodes were titled "Invasion!". "Invasion!" sees Barry Allen recruit Kara Danvers to his Earth to help his team, Oliver Queen and his team, and the Legends defeat the alien race known as the Dominators.

Development for a crossover between the three series, along with Supergirl, began in May 2016 after it was revealed that Supergirl would move to The CW from CBS for its second season. By the following September, the scripts for each episode had been written, with filming occurring shortly after, in October 2016. The premise and episode titles were also revealed that month. "Invasion!" sees all of the main cast members for each series appear in at least their own series, with Melissa Benoist appearing as Supergirl across the entire crossover. Multiple actors and characters from previous Arrow seasons also return to reprise their roles, as Arrow's episode doubled as its 100th.

The three episodes of the crossover all received positive reviews, with critics praising the interactions between all of the various actors from each series, and the fact that each episode was also able to progress season storylines while still being part of the crossover. Conversely, the Dominators storyline felt like the weakest part of the crossover, with reviewers feeling the alien race had unclear motivations throughout. Ratings for the episodes were exceptional, with each breaking records in viewership and the 18-49 rating, contributing to the most-watched week on The CW in six years.