Someone else knows something, some one had to tell Ned where to find them. 7 knights from the North aren't just going to stumble on a tower in the Dorne hills.
Here are people who I think *may* have known (Besides the obvious of Ned and Howland who definitely knew/know):
These are my most likely candidates:
-Benjen Stark (He was the closest to Lyanna out of all of his siblings and there's been Crackpot theories about why he took the black, especially since Brandon died and was no longer a 3rd son after that. He may have helped Lyanna run off with Rhaegar and once Ned came back to Winterfell he could've put two and two together/surmised that Jon was Lyanna's son. He knew how honorable Ned was. Benjen also told Jon not to join the Watch immediately and that he wasn't experienced enough. He never had sex with a women, no kids, etc. and wouldn't know how much he was truly giving up, which could have a double meaning in regards to his parentage.)
-Wylla (Edric Dayne knew he was a milk brother to Jon, but I think Wylla knew so that she could be in on the secret/know how to play her role in protecting Jon)
-Ashara Dayne and some other Daynes (they stopped in Starfall on the way back and Ashara may have known where Rhaegar and Lyanna were hiding out)
-Varys (I think this is less likely but some people think that Varys knows but IMO he never knew. I think he would've done something about it if it was going to interfere with his Aegon plot).
-Ser Barristan (Barristan told Dany that Rhaegar was 'fond' of Elia Martell but loved his Lady Lyanna. I still think this is less likely but Barristan knows a lot of shite.)
Characters who I think have or will have enough information to reach the R+L=J conclusion first and realize who Jon truly is:
-Ser Barristan (if he doesn't know already)
-Tyrion Lannister (Tyrion seems to connect things better than most characters/learn about things better)
This post was edited on 8/22 at 8:31 am