For me? Eugenio Narvaez, and Valerio Salcedo - both of them generals in the Spanish Army.
I was playing V2:HoD with A:1836 enabled. The plague began in China, so I had a couple of years to prepare my defenses. I basically abandoned the overseas possessions, to defend the peninsula.
I built forts all along the Pyrenees border towns, reorganized my troops to be "standard stacks" of 5 ART 1 HUS - filling each of them in with 4 INF from mobilization.
The hordes arrived in Pamplona, and they were merciless. More kept pouring in day by day. At some points, the undead outnumbered the Spanish defenders more than fifteen to one. But through all of that, through the entire battle (thanks to unit cycling and replenishment), none of the defenses ever broke.
It was looking grim for a while. At one point, it was >1,000,000 undead to only 63,000 Spanish defenders. Surely the line would break. But no, not Narvaez or Salcedo. Those generals' men dutifully and methodically held the line.
The Siege of Pamplona lasted almost four straight years. Other than some minor containment operations along the Portuguese border, it was the only major engagement that the Spanish Army really had.
All told, Spain lost ~133,000 soldiers at Pamplona. The undead horde, however, was entirely routed - with at least ten million lost. That's a loss ratio of 75.2:1.
(pure conjecture, not shown in-game)
Spain was the only country to survive the hordes more-or-less intact, and keep on humming. The great countries of Prussia and France and Turkey were swept aside, but Spain survived. Some said it was a miracle, given by God. In reality, it was all because of those men who refused to budge at Pamplona, and those men who worked tirelessly in the factories to keep the ammunition, weapons, medical supplies, and canned food coming in.
After retiring from the military, Narvaez would be appointed by the monarch as Prime Minister. Under his governments, Spain successfully restored the old American and Pacific empire, repopulating it with Spanish settlers.
Determined not to make the same mistake of savagely exploiting the settlers and the natives under the previous empire, Narvaez appointed his friend and brother-in-arms, Salcedo, as Viceroy of America (civil governor of all the colonies in America that didn't yet have organic state governments).
Under Salcedo's governorship, a continent-spanning rail system was built. This made it possible to go all the way from Las Californias in the north, to Santiago in the south; or from Texas in the north, all the way to the mouth of the Rio de la Plata. It was his crowning achievement.
Spain had Narvaez and Salcedo at exactly the correct times. They were there in Spain's darkest hours, and they helped Spain basically rebuild the world.
And after retiring politically, each of them lived relatively quiet lives. Narvaez had a biographer write a memoir (with whole sections devoted the Siege of Pamplona), and Salcedo started an architecture firm - specializing in railroads, fortifications, harbors, etc. Salcedo wrote a lot about politics and systems of government, as well.
And in the year 1867, both of them passed on.
Church bells rang throughout the empire every ten minutes, every day, for months on end. One toll represented one undead those men repelled at Pamplona.
Their mausolea are now Spanish national treasures, located right in the heart of Madrid. There is a third mausoleum, commemorating every single man who fought and/or died during the siege.