Which people do you think deserve to be more well known?
Jacobus Arminius-Dutch theologian
Lewis Cass-American politician and statesman
John MacArthur-American clergyman
James K. Polk-American president
Charles Spurgeon-British clergyman
Zhang Xianzhong-Chinese warlord (and the most insane leader to ever rule over a significant amount of territory)
Jo Stafford. Considering she is the biggest female recording artist for the first half of the 1900s. (From 1900 to 1950) and considering how much music she recorded and how many styles, (Jazz, Big Band, Swing, Rock n Roll, Comedy, Folk, Vocals, Blues) she ought to be well known today. But few have heard of her.
Ann Sothern is another one. She did all styles of acting from dram (“Letter To Three Wives,” “Whales of August” to comedy). She deserves to be more famous.
Then there’s Carl Mahakian who isn’t famous because, according to Carol Brady, he quit 
Hong Xiuquan - A Chinese man who became convinced in 1844 that he was the living brother of Jesus Christ. What’s surprising was he also convinced several million other people of this and a civil war resulted between his followers and the Chinese government which lasted from 1850 to 1864. It was one of the biggest wars in history (25 million people died) but most people have never heard of it.
Not a person, but I think that the Islamic Golden Age is something that deserves at least some mention in history classes.The Renaissance almost certainly owes far more to the Islamic world than it does to Europe itself and yet history (at least in my classes) is taught like the Renaissance happened all on its own.
How do we know whether or not we’ve heard of it, since we still don’t know what it was called? You didn’t mention it’s known as the Taiping Rebellion. 
My nominee is Stanislav Petrov, who probably saved more than 25 million lives.
That’s a really good example. I’d never heard of him, shows how little Chinese history I know.
I did have a candidate to propose, but fittingly I can’t remember his name. He was the scientist who originally performed the experiment to measure the weight of the earth (I think, or possibly he was measuring the gravitational constant).
<Edit - I was thinking of Henry Cavendish>
Tabitha King–Incredible novelist, overshadowed ny her husband Stephen.
Anne Morrow Lindberg–Her “Gift From The Sea” is truly amazing.
Several Revolutionary War officers – whose names I can’t recall now. They’ve been overshadowed by the big names.
One person who’s finally getting his due is Henry “Ox” Knox, who was the fellow responsible for hauling all those cannon from Fort Ticonderoga to Boston and getting them set up in complete secrecy, leading to the bloodless conquest of Boston – truly an important moment in the Revolutionary War. Even more than the Battle of Bunker Hill (which Knox participated in), I think it established the American forces as serious opponents. Knox went on to be Washington’s chief of artillery, and was in the boat with Washington crossing the Delaware. Then he went on to be the first US. SEcretary of War.
Fort Knox is named after him, but I’ll bet most people don’t know that.
He’s been given center stage in lots of recent books about the Revolution, but I sure didn’t hear about him in school, or in Boy Scouts. My favorite bit about him I learned in the book Don’t Know Much About History, which tells the story of Washington getting into the boat on the Delaware and saying “Move that fat ass, Henry. But not too fast or you’ll swamp the boat.”
In the US the Civil War gets more attention than the Revolution so it’s not a surprise Knox is not well known.
Alice Paul, whose political extremism (and pretty good looks) forced the hand to FINALLY pass women’s sufferage.
ETA: I taught Civil Rights in Sunday School last year, and learned about the Birmingham Children’s March. Why that isn’t taught in schools - it absolutely fascinated the forth graders.
Count Gioacchino Vincenzo Raffaele Luigi, who later became Pope Leo XIII, is well-known among Catholics but not among other people. He was instrumental in creating and spreading a great many ideas ranging from minimum wage to religious freedom.
There’s a lot of ignorance about the Civil War as well. If you asked most people to describe the Civil War in terms of the personalities involved you’d get a story like this:
Lincoln was in charge of the north and Davis was in charge of the south. Lee commanded the southern army. McClellan commanded the northern army but he was no good so Lincoln put Grant in charge of the northern army. Lee’s second-in-command was Jackson (who died) and Grant’s second-in-command was Sherman (who didn’t die). Lee surrendered to Grant and the war was over. Then Lincoln get shot by Booth.
No mention of Beauregard, Benjamin, Breckinridge, Buell, Burnside, Butler, Chase, Farragut, Halleck, Hamlin, Hood, Hooker, Johnston (Albert or Joseph), Longstreet, McDowell, McPherson, Meade, Memminger, Pickens, Rhett, Rosecrans, Schofield, Scott, Seward, Sheridan, Stanton, Stephens, Thomas, Wade, Walker, or Welles.
Canadian doctor who developed tools for thoracic surgery, then went overseas to work with the leftists in the Spanish Civil War; in Spain he developed mobile blood-transfusion techniques. Later he went to China and did similar work. There are streets and other places named for him in Canada, Spain, and China–my aunt lived on Bethune Street in Peterborough.
But you might not have heard of him because he was (gasp) a Communist.
Well, how many people has his tech saved so far compared to those that communism killed? 
I’m sure he’ll pay himself off at some point, of course.
Plus, she was the voice of “My Mother, the Car”.
Wait, maybe that’s why she languishes in obscurity.
How about the dude that received the nobel prize for “inventing” holograms?
Given how much buzz (and research papers) holograms have generated over all these years you’d think he would be more well known.
Interestingly enough, he “invented” them to solve a different and rather boring problem. And it didnt really work practically for that in the first place.
Fritz Haber - developed the process for synthesizing ammonia using nitrogen in the air, making cheap fertilizer possible, “responsible for sustaining one-third of the Earth’s population”. Haber process - Wikipedia
Norman Borlaug - developed high-yield wheat, which is credited with saving a billion people from starvation, for which he received the Nobel Peace Prize. Norman Borlaug - Wikipedia
And we should also mention the Islamic Golden Age wouldn’t have happened without over 100 years of the “spread” of Islam to al-Andalus and, for a short while, into France.
Witold Pilecki.
He was a member of the Polish Home Army who got caught by the Germans on purpose to infiltrate the Auschwitz concentration camp. He wrote a detailed report on his experiences, which convinced the Allies of the reality in the camps. Despite doing back-breaking manual labor in terrible conditions just like all the other inmates, he managed to organize resistance cells, which would try to take over the camp in the event that the allies would send help(which they never did as we know now).
He eventually escaped and joined the Home Army’s efforts elsewhere, and was rewarded for all this after the war in the typical Stalinist fashion of getting a show trial and being executed as an “imperialist spy” by the new Polish puppet government.
This guy deserves to have a movie made out of his life. A good one.
His report on Auschwitz can be read here.
Darn, you beat me to it.
The fact that I first learned about Dr. Borlaug from a magician/comedian rather than in school doesn’t exactly reflect well on education in my province.