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.
Everything i watched before i used Trakt.
Here's an alphabetical list of what i have watched:
The 100 S1
Arrow S1x01 - S4x15
Avatar: The Last Airbender S1 - S4 (Complete Series)
Better Call Saul S1x01 - S1x07
Breaking Bad S1 - S5 (Complete Series)
Chicago Fire S1x01 - S1x02
Constantine S1x01 - S1x06
The Flash (2014) S1x01 - S2x15
Game of Thrones S1 - S5
Gotham S1x01 - S2x13
How I Met Your Mother S1x01 - S4x02
The Last Ship S1 - S2
Legends of Tomorrow S1x01 - S1x07
The Legend of Korra (Complete Series)
The Man in the High Castle S1x01 - S1x05
Marvel's Agent Carter S1x01 - S1x05
Marvel's Daredevil S1
Marvel's Jessica Jones S1x01
Mr. Robot S1x01 - S1x05
Prison Break (Complete Series)
Star Wars: The Clone Wars S1 - S6 (Complete Series)
Star Wars Rebels S1 - S2
Supergirl S1x01 - S1x11
Teenage Mutant Ninja Turtles (2003) S1 - S7(Complete Series)
Teenage Mutant Ninja Turtles (2012) S1 - S3
Episodes seen twice:
Arrow S1x01 - S4x09
The Flash S1x01 - S2x09