User blog comment:ZokeiR/Possible Grand Servants/@comment-1458758-20170422201114

Grand Saber - Artoria Pendragon almost certainly qualifies.

Grand Archer - Heracles Literally the most legendary hero on the planet.

Grand Lancer - Karna I'd say is a good chance, but Scathy, the god slayer seems a great candidate as well.

Grand Rider - Noah would be great, but I can't think amongst the guys who exist already, maybe Ramesses?

Grand Assassin - Already seen with Hassan-i-Sabbah

Grand Caster - Already seen several with the ability including Merlin, Solomon and Gilgamesh

Grand Berserker - Literally no idea, like Harold Fairhair maybe?