MCU: 12 Things We Learned From 4Chan's Latest Marvel Movies "Leak"
9. Lady Death Will Appear In Thor: Ragnarok
The Rumour
Thor: Ragnarok will set up Avengers: Infinity War and will feature an appearance from Lady Death herself.
Response
I call bullsh*t on this. Not the first part - that's pretty much a given, because of the timings, and the fact that all of the Infinity Stones should have been revealed by then. If the other rumour that Loki will be the one to tell Thanos the locations when under duress is indeed true, then Thanos will be one step closer to unifying the gems.
The issue is that Lady Death might be too much of a religious character to be a viable option for the MCU. It makes far more sense that Thanos would instead fall for Hela and want to impress her with a gross act of mass-killing. She will have already been established in the MCU by then, and the unique Asgardian mythology means having a Death figure won't complicate things too much. It would be silly to do it any other way.