<P> In August 2015, it was confirmed that Ryan would appear in Arrow's fourth - season episode "Haunted" for a "one - time - only - deal". Guggenheim said, "This is something the fans were clamoring for," praising DC for being so "magnanimous and generous in giving us this one - time dispensation ." Due to Arrow and Constantine sharing the same studio, the producers of Arrow were able to use Ryan's original outfits: "The trench coat, the tie, the shirt...the whole wardrobe is being taken out for (sic) storage and shipped up to Vancouver (where Arrow shoots)." John Badham, a director on Constantine, directed the episode that Constantine appears in . Mericle confirmed that this version of Constantine would be the same character that had appeared in Constantine . On filming the episode, Guggenheim referred to it as "a Constantine / Arrow crossover" and felt that "we got the chance to extend Matt Ryan's run as Constantine by at least one more hour of television . I think you'll see he fits very neatly into our universe . It never feels forced". </P> <P> In July 2017, Guggenheim indicated that "really good conversations" had taken place with Ryan to appear again in the Arrowverse, and in October 2017, it was revealed that Ryan would appear in two episodes of the third season of Legends of Tomorrow, "Beebo the God of War" and "Daddy Darhkest", with the appearance taking place chronologically after "Haunted", revisiting the setting of Arrow's fourth season and the events following that season's final episode . Klemmer described the tone of the episodes as "The Exorcist meets One Flew Over the Cuckoo's Nest". Ryan was made a series regular for the fourth season of Legends of Tomorrow . </P> <P> In April 2015, to celebrate the season three finale of Arrow and season one finale of The Flash, The CW released a short promo titled "Superhero Fight Club". The short features characters from Arrow and The Flash battling each other in a hero vs. villain showdown . Characters include The Arrow, Flash, Arsenal, Black Canary, Dark Archer, Reverse - Flash, Captain Cold, Heat Wave, Firestorm, Ra's al Ghul, and Atom in a cage match fight, with Black Canary and Arsenal vs. Dark Archer, Arrow vs. Ra's al Ghul, Flash vs. Captain Cold and Heat Wave, which is interrupted by Reverse - Flash, until Firestorm intervenes and the Atom makes an appearance at the end . In September 2016, The CW released the promo "Superhero Fight Club 2.0" to promote the start of the 2016 - 17 season with the addition of Supergirl to their lineup, as well as their new mobile app, where the promo could exclusively be viewed initially . The new Superhero Fight Club sees Green Arrow, Flash, Atom, Firestorm, White Canary and Supergirl go up against a new fight simulator created by Cisco Ramon and Felicity Smoak, while John Diggle and Martian Manhunter observe . After defeating the simulator, Cisco releases Gorilla Grodd into the arena for the heroes to face . In January, 2018, The CW released the promo "Suit Up" of the various heroes putting on their costumes in order to promote the return of Arrow, The Flash, Legends of Tomorrow, and Supergirl from their first mid-season break, as well as the premiere of Black Lightning . </P> <Table> <Tr> <Th> Series </Th> <Th_colspan="2"> Season </Th> <Th_colspan="4"> Originally aired </Th> <Th_colspan="3"> Nielsen ratings </Th> </Tr> <Tr> <Th> First aired </Th> <Th> Viewers (in millions) </Th> <Th> Last aired </Th> <Th> Viewers (in millions) </Th> <Th> Average viewers (in millions) </Th> <Th> Rank </Th> <Th> 18--49 rating (rank) </Th> </Tr> <Tr> <Td> Arrow </Td> <Td> </Td> <Td> </Td> <Td> October 10, 2012 (2012 - 10 - 10) </Td> <Td> 4.14 </Td> <Td> May 15, 2013 (2013 - 05 - 15) </Td> <Td> 2.77 </Td> <Td> 3.68 </Td> <Td> 130 </Td> <Td> 1.2 (125) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 9, 2013 (2013 - 10 - 09) </Td> <Td> 2.74 </Td> <Td> May 14, 2014 (2014 - 05 - 14) </Td> <Td> 2.37 </Td> <Td> 3.28 </Td> <Td> 128 </Td> <Td> (119) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 8, 2014 (2014 - 10 - 08) </Td> <Td> 2.83 </Td> <Td> May 13, 2015 (2015 - 05 - 13) </Td> <Td> 2.83 </Td> <Td> 3.52 </Td> <Td> 135 </Td> <Td> 1.3 (111) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 7, 2015 (2015 - 10 - 07) </Td> <Td> 2.67 </Td> <Td> May 25, 2016 (2016 - 05 - 25) </Td> <Td> 2.19 </Td> <Td> 2.90 </Td> <Td> 145 </Td> <Td> 1.1 (110) </Td> </Tr> <Tr> <Td> </Td> <Td> 5 </Td> <Td> October 5, 2016 (2016 - 10 - 05) </Td> <Td> 1.87 </Td> <Td> May 24, 2017 (2017 - 05 - 24) </Td> <Td> 1.72 </Td> <Td> 2.21 </Td> <Td> 147 </Td> <Td> 0.8 (133) </Td> </Tr> <Tr> <Td> </Td> <Td> 6 </Td> <Td> October 12, 2017 (2017 - 10 - 12) </Td> <Td> 1.52 </Td> <Td> May 17, 2018 (2018 - 05 - 17) </Td> <Td> 1.35 </Td> <Td> 1.76 </Td> <Td> 181 </Td> <Td> 0.6 (163) </Td> </Tr> <Tr> <Td> The Flash </Td> <Th> </Th> <Td> </Td> <Td> October 7, 2014 (2014 - 10 - 07) </Td> <Td> 4.83 </Td> <Td> May 19, 2015 (2015 - 05 - 19) </Td> <Td> 3.87 </Td> <Td> 4.62 </Td> <Td> 118 </Td> <Td> 1.7 (90) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 6, 2015 (2015 - 10 - 06) </Td> <Td> 3.58 </Td> <Td> May 24, 2016 (2016 - 05 - 24) </Td> <Td> 3.35 </Td> <Td> 4.25 </Td> <Td> 112 </Td> <Td> 1.7 (69) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 4, 2016 (2016 - 10 - 04) </Td> <Td> 3.17 </Td> <Td> May 23, 2017 (2017 - 05 - 23) </Td> <Td> 3.04 </Td> <Td> 3.50 </Td> <Td> 120 </Td> <Td> 1.4 (78) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 10, 2017 (2017 - 10 - 10) </Td> <Td> 2.84 </Td> <Td> May 22, 2018 (2018 - 05 - 22) </Td> <Td> 2.16 </Td> <Td> 3.04 </Td> <Td> 151 </Td> <Td> 1.1 (108) </Td> </Tr> <Tr> <Td> Supergirl </Td> <Td> </Td> <Td> </Td> <Td> October 26, 2015 (2015 - 10 - 26) </Td> <Td> 12.96 </Td> <Td> April 18, 2016 (2016 - 04 - 18) </Td> <Td> 6.11 </Td> <Td> 9.81 </Td> <Td> 39 </Td> <Td> 2.4 (27) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 10, 2016 (2016 - 10 - 10) </Td> <Td> 3.06 </Td> <Td> May 22, 2017 (2017 - 05 - 22) </Td> <Td> 2.12 </Td> <Td> 3.12 </Td> <Td> 129 </Td> <Td> 1.0 (115) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 9, 2017 (2017 - 10 - 09) </Td> <Td> 1.87 </Td> <Td> June 18, 2018 (2018 - 06 - 18) </Td> <Td> 1.78 </Td> <Td> 2.82 </Td> <Td> 154 </Td> <Td> 0.9 (125) </Td> </Tr> <Tr> <Td> Legends of Tomorrow </Td> <Td> </Td> <Td> </Td> <Td> January 21, 2016 (2016 - 01 - 21) </Td> <Td> 3.21 </Td> <Td> May 19, 2016 (2016 - 05 - 19) </Td> <Td> 1.85 </Td> <Td> 3.16 </Td> <Td> 135 </Td> <Td> 1.2 (104) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 13, 2016 (2016 - 10 - 13) </Td> <Td> 1.82 </Td> <Td> April 4, 2017 (2017 - 04 - 04) </Td> <Td> 1.52 </Td> <Td> 2.57 </Td> <Td> 141 </Td> <Td> 0.9 (127) </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> October 10, 2017 (2017 - 10 - 10) </Td> <Td> 1.71 </Td> <Td> April 9, 2018 (2018 - 04 - 09) </Td> <Td> 1.41 </Td> <Td> 2.24 </Td> <Td> 170 </Td> <Td> 0.8 (137) </Td> </Tr> </Table>

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