In the Wheel of Time TV series by Amazon, a character named Mazrim Taim, a false Dragon from Saldaea, has been mentioned in passing a couple of times in season 2. He has not yet been seen on screen or had any direct impact on the plot, but, given events in the books, he is likely to in time.
=== MAJOR SPOILERS FOR THE BOOKS FOLLOW ===
In the novels by Robert Jordan which are the source material for series, Mazrim Taim is an important character in later books. He is appointed by Rand al'Thor to teach men at the "Black Tower," a haven for men who can channel. He is also revealed to be a Darkfriend, and is responsible for forcibly converting many of the men at the Black Tower into Darkfriends as well.
A widespread theory after Taim's initial appearance is that he was actually the Forsaken Demandred, who had been introduced at around the same time as Taim and had a similar personality. The topic was passionately debated for a time, until Robert Jordan put the matter to rest by having both characters appear in the same place at the same time in later books.
Currently, it is believed based on Jordan's notes that Taim was in fact intended to be Demandred in his original plans, but that he later decided that this was too obvious and changed his mind, and that this is the reason for the somewhat confusing and contradictory evidence in the text.
But, the TV show is only loosely following the plot of the books, and it is likely that some characters will be merged or eliminated to simplify the plot for television purposes. This could include Taim and Demandred.
Will the good ship Taimendred sail again?
This market resolves as YES if Mazrim Taim, the false Dragon from Saldaea, is at any time revealed to be one of the Forsaken. (Any Forsaken, just in case Demandred is merged with one of the others.) Resolves NO otherwise.
Considerations:
For these purposes, "Forsaken" means a channeler who was imprisoned along with the Dark One at the end of the Age of Legends, and then freed 3000 years later in the "present day." A person who was born in the "present" would not count, even if they were to be given the title of "Forsaken" or "Chosen" at some point in their life.
It still counts if a "real" Mazrim Taim appears initially, and is later replaced by a Forsaken (or vice versa). As long as a Forsaken is, at any point, falsely using the name "Mazrim Taim," it counts.
In the event that the show is cancelled or otherwise ends before its conclusion, I will leave the market open for one year after that becomes known. I will then resolve based on whatever material exists at the time, including e.g. interviews with the showrunners discussing what their future plans for the show would have been.
I will not be betting in this market.