Jesus
This one is a bit controversial. Most modern historians do believe that Jesus was a real person, but most will agree that his portrayals in the Bible are quite inaccurate and likely not historically reliable. Of course, he is undeniably the most important and central figure in Christianity.
King Solomon
Just as scholars hypothesize about Jesus, most believe that King Solomon was a real person but most experts across biblical archeology tend to agree that it is difficult to trace historical accuracy to the bible stories we are all familiar with.