Arrowverse viewing order:
[pending on update...]
This is the simplified list for easy viewing order for Arrowverse!
Webisodes (you can find most of these videos at YouTube or at CWtv website):
Constantine has a cameo in Arrow S4E05. I do recommend you to watch this series, but there's no must. But he might get back into the Arrowverse one day. (and I also would recommend to watch it in this order: 1, 6, 2-5, 7-13. Episode 6 was shot to air as the second episode of the series)
I have added Supergirl Season 1 before the crossover episode to the list. You can watch it basically whenever you want, as long as you watch it before Flash S2E18 or after Flash S2E18 (I personally prefer to watch it before Flash episode, but both ways work). Also S1E04 and S1E05 were aired ouut of original order. Episode 5 should be viewed before episode 4
Constantine: City of Demons: So it appears that Constantine: City of Demons is not a continuation of the Constantine series and so it is not included in Arrowverse. Instead it's in the same universe as Justice League Dark (so it's in DC Animated Universe). But for now I'm going to leave it in the list, as it still explains things like "Newcastle" and etc. But they may get connected, as Constantine will becomes a regular on DC: Legends next season. So we will wait and see.
Crisis on Infinite Earths: Starting with Supergirl part 1 - Sunday, December 8th, following with Batwoman part 2 next day on Monday, December 9th, with The Flash part 3 on Tuesday, December 10th and then starting the new year off with Arrow part 4 Tuesday, January 14, 2020, right after followed by the last part of the Crossover event on the same day, Legends of Tomorrow part 5 ending the Crisis on Infinite Earths crossover event. This event will also tie-in Black Lightning into the arrowverse universe among other things.
There will be a Arrow spin-off series following Mia (Katherine McNamara) also Canaries Laurel Lance and Dinah Drake will be part of the spin-off.
Earths / Connected Shows
The Flash (1990) - earth 90
Supergirl -earth 38
Freedom Fighters: The Ray - earth X
Birds of Pray
Comic books that also follow the series:
Based on koomy's list from IMDb with some additions: http://www.imdb.com/list/ls074499769/
Contains the following shows: Arrow, The Flash, Vixen, Constantine, DC's Legends of Tomorrow and Supergirl (for now, more will be added as they are released).
Comments are welcome in order to make this list the most accurate possible.
• "Arrow: Blood Rush" is actually a BOSE commercial in six parts lasting about six minutes in total (available on Youtube). While they are not really mandatory, they should be watched between episode 5 and 6 of season 2.
• "The Flash: Chronicles of Cisco" is a four part short also available on Youtube, not mandatory.
• Constantine: Episodes can be slotted in at will as long as you watch them before S04E05 of Arrow. They're not mandatory as the show is somewhat inachieved but you might enjoy the character. Update: An animated series being planned, the story might continue from where the show stopped.
• DC's Legends of Tomorrow: I included the first special episode before the first episode because this special kinda introduce the show explaining where the characters are from (in a "making-of" style) whitout much spoilers while managing to refresh our memory about them.
• Supergirl: Episodes can be slotted in at will until S01E17 (included) as long as they're seen before Arrow S04E19. Episode 18 is the first time Supergirl get to meet a character from the Arrowverse (The Flash).
Side note: For Season 1, you may encounter a wrong episode order depending on the sources (only some, I didn't meet this problem): the right order would then be 1-2-3-5-4-6 to end, but it is not a big deal as it actually doesn't change much.
• "Freedom Fighters: The Ray" will be integrated as soon as we have informations about it.
• "Constantine" (Planned animated series) will come up at some point, it might continue the story from where the TV show stopped it, more news to come.
THIS LIST WILL BE UPDATED PERIODICALLY. (Last update: 2017-03-09)
This is a list with episodes of various DC Entertainment TV series in internal chronological order, according to this list: https://geekritique.net/2015/05/19/arrow-and-the-flash-chronological-order
2017-10-27: The post on geekritique.net, which this list is based on, hasn't been updated in roughly half a year, so I consider it to be abandoned. Thus I advise anyone using this list to use my other Trakt Arrowverse list instead: https://trakt.tv/users/nidunc/lists/arrowverse-viewing-order-according-to-thetimelinesite-com.
Besides, the geekritique.net list didn't include all episodes in the first place (see the above bullet point for an example), while thetimelinesite.com does include all episodes (and is still being updated).
I will still be checking geekritique.net from time to time, but I presume it won't be updated in the future.
Every episode i have watched in 2016.
The 100 S2 - S3
11.22.63 (Complete Series)
Arrow S4x16 - S5x09
Better Call Saul S1x08 - S2x10
Burn Notice S1x01 - S2x07
Chicago Fire S1x03 - S5x08
Chicago Med S1x01 - S2x08
Chicago P.D. S1x01 - S4x08
Constantine S1x07 - S1x13 (Completed)
The Flash S2x16 - S3x09
Game of Thrones S6
Gotham S2x14 - S3x11
Homeland S1x01 - S2x12
House Of Cards S1 - S3
How I Met Your Mother S4x03 - S7x04
The Last Ship S3
Legends Of Tomorrow S1x08 - S2x08
Lucifer S1x01 - S2x10
The Man in the High Castle S1x06 - S2x03
Marvel's Agent Carter S1x06 - S2x10 (Completed)
Marvel's Daredevil S2
Marvel's Jessica Jones S1x02 - S1x13
Marvel's Luke Cage S1
Mr. Robot S1x06 - S2x12
Narcos S2x01 - S2x02
Supergirl S1x12 - S2x08
Episodes seen for the 2nd time:
The Flash S1x01
Narcos S1x01 - S1x03