These are the most significant historical figures who got the most research and study, according to Wikipedia. The most researched nationality is Germans with 21 figures, followed by 13 Americans, 7 Chinese, and 5 Russians.
Top 100 Most Researched Historical Figures
1. Karl Marx (1818—1883), German philosopher — 3180 work.
2. Immanuel Kant (1724—1804), German philosopher, builder of Neo-Kantianism- 2005 work
3. Vladimir Lenin (1870—1924), Russian communist revolutionary, politician, and political theorist, leader of October Revolution and founder of Soviet Union - 1970 work
4. Abraham Lincoln (1809—1865), American politician and lawyer — 1933.
5. Adolf Hitler (1889—1945), German politician who was the leader of the Nazi Party — 1773.
6. Friedrich Hegel (1770—1831), German philosopher — 1654.
7. Sigmund Freud (1856—1939), Austrian neurologist and the founder of psychoanalysis — 1537.
8. Mahatma Gandhi (1869—1948), leader of the Indian independence movement in British-ruled India — 1487.
9. Friedrich Nietzsche (1844—1900), German philosopher — 1468.
10. Martin Luther (1483—1546), German professor of theology, composer, priest, monk and a seminal figure in the Protestant Reformation— 1390.
11. Thomas Aquinas (1225?—1274), Italian Dominican friar, catholic priest, and doctor of the church— 1382.
12. Martin Heidegger (1889—1976), German philosopher — 1300.
13. Platon (428 BC —348 BC), Philosopher in Classical Greece — 1263.
14. Aristotales ( 384 BC— 322 BC), Greek philosopher and scientist — 1227.
15. Mao Zedung (1893—1976), Chinese communist revolutionary and founding father of the People's Republic of China — 1150.
16. George Washington (1732—1799), American soldier and statesman. — 1124.
17. Joseph Stalin (1879—1953), Leader of the Soviet Union — 1108.
18. Christopher Columbus (1451?—1506) — Italian explorer, navigator, colonizer — 1092.
19. Napoleon (1769—1821) — French military and political leader— 1002.
20. Franklin Roosevelt (1882—1945), American statesman and political leader — 988.
21. Augustinus (354—430), early Christian theologian and philosopher — 950.
22. Richard Wagner (1818—1883), German composer — 840.
23. Carl Gustav Jung (1875—1961), Swiss psychiatrist and psychotherapist — 826.
24. Wolfgang Amadeus Mozart (1756—1791), Austrian composer — 759.
25. Johann Wolfgang von Goethe (1749—1832), German writer and statesman — 758.
26. Thomas Jefferson (1743—1826), 3rd U.S. President — 755.
27. René Descartes (1596—1650), French philosopher, mathematician, and scientist — 755.
28 Jean-Jacques Rousseau (1712—1778), Francophone Genevan philosopher, writer, and composer — 735.
29. Benjamin Franklin (1706—1790), American politician and scientist — 709.
30. Theodore Roosevelt (1858—1919), 26th President of the United States — 708.
31. Ludwig Wittgenstein (1889—1951), Austrian-British philosopher — 694.
32. Ludwig van Beethoven (1770—1827), German composer and pianist — 689.
33. Lev Tolstoy (1828—1910), Russian author — 681.
34. Søren Kierkegaard (1813—1855), Danish philosopher, theologian, poet, social critic and religious author — 679.
35. Edmund Husserl (1859—1938), German philosopher — 659.
36. Woodrow Wilson (1856—1924), 28th President of the United States — 641.
37. Sokrates ( 469 BC — 399 BC), Greek philosopher — 601.
38. Johann Sebastian Bach (1685—1750),German composer — 599.
39. Charles de Gaulle (1890—1970), French general and statesman — 594.
40 Friedrich Engels (1820—1895), German philosopher, social scientist, journalist, and businessman — 584.
41. John F. Kennedy (1917—1963), 35th President of the United States — 572.
42. Baruch Spinoza (1632—1677), Dutch philosopher — 568.
43. Albert Einstein (1879—1955), German theoretical physicist — 553.
44. Max Weber (1864—1920), German sociologist, — 546.
45. Leonardo da Vinci (1452—1519),Italian Mathematician and painter — 536.
46. Winston Churchill (1874—1965), British statesman — 533.
47. Pablo Picasso (1882—1973),Spanish painter, sculptor, printmaker, ceramicist, — 513.
48. Pope John Paul II (1920—2005), Catholic religious leader — 507.
49. Jesus (7-2 BC— 30-33 AD ), Central figure of Christianity. — 500.
50. Karl Barth (1886—1968), Swiss Reformed theologian — 492.
51. Rabindranath Tagore (1861—1941), Indian author — 488.
52. Jean Calvin (1509—1564), French theologian and pastor — 483.
53. Jean-Paul Sartre (1905—1980), French philosopher, playwright, novelist — 479.
54. Charles Darwin (1809—1882), English naturalist and geologist — 468.
55. Michelangelo (1475—1564), Italian sculptor, painter, architect — 465.
56. William Shakespeare (1564—1616), English poet, playwright, and actor — 454.
57. Rembrandt (1606—1669), Dutch draughtsman, painter and printmaker. — 452.
58. Alexander Pushkin (1799—1837), Russian poet, playwright, and novelist— 443.
59. Gottfried Leibniz (1646—1716), German polymath and philosopher — 442.
60. Frédéric Chopin (1810—1849), Polish composer and virtuoso pianist — 441.
61. Deng Xiaoping (1904—1997), Chinese revolutionary and statesman — 440.
62. David Hume(1711—1776), Scottish philosopher, historian, economist — 436.
63. Pierre Teilhard de Chardin (1881—1955), French idealist philosopher and Jesuit priest — 435.
64.Fyodor Dostoyevsky (1821—1881),Russian novelist, short story writer, essayist, journalist and philosopher — 431.
65. Dante (1265—1321), Italian author — 427.
66. Jean Piaget (1896—1980), Swiss clinical psychologist — 420.
67. Gautama Buddha (563 BC — 483? BC), Founding Figure of Buddhism — 411.
68. John Dewey (1859—1952), American philosopher, psychologist, and educational reformer — 387.
69. Ronald Reagan (1911—2004), 40th U.S. President — 383.
70. Pascal (1623—1662), French mathematician, physicist, inventor, writer — 381.
Mustafa Kemal Atatürk (1881—1938), Turkish army officer, revolutionary, and founder of the Republic of Turkey — 379.
72. Niccolò Machiavelli (1469—1527),Italian philosopher — 372.
73. Jacques lacan (1901—1981), French psychoanalyst and psychiatrist — 365.
74. Maksim Gorky (1868—1936), Russian author — 365.
75. Dwight D. Eisenhower (1890—1969),34th U.S. President — 359.
76. Voltaire (1694—1778), French Enlightenment writer, historian, and philosopher — 359.
77. Michel Foucault (1926—1984), French philosopher — 350.
78. Antonio Gramsci (1891—1937), Italian neo-Marxist theorist and politician. — 344.
79. John Locke (1632—1704), English philosopher and physician — 343.
80. Henri Bergson (1859—1941), French philosopher — 341.
81. Confucius (551 BC — 479 BC), Chinese teacher, editor, politician, and philosopher of the Spring and Autumn period of Chinese history — 335.
82. Galileo Galilei (1564—1642),Italian polymath: astronomer, physicist, engineer, philosopher, and mathematician — 332.
83. Thomas Hobbes (1588—1679), English philosopher— 330.
84. Francisco Goya (1746—1828), Spanish romantic painter and printmaker — 328.
85. Sri Aurobindo (1872—1950), Indian nationalist, philosopher, yogi, guru and poet— 320.
86. George Bush (d. 1946), 43rd U.S. President — 312.
87. Jürgen Habermas (d. 1929), German sociologist and philosopher — 308.
88. Victor Hugo (1802—1885), French poet, novelist, and dramatist — 307.
89. Mihail Gorbaçov (d. 1931), frmer Soviet statesman — 306.
90. Alexander the Great (356 BC — 323 BC), king of the Ancient Greek kingdom of Macedon— 303.
91. Johann Gottlieb Fichte (1762—1814), German philosopher — 295.
92. Walt Whitman (1819—1892), American poet, essayist, and journalist. — 294.
93. Che Guevara (1928—1967), Argentine Marxist revolutionary, physician, author, guerrilla leader, diplomat, and military theorist. — 294.
94. Jacques Derrida (1930—2004), French philosopher, — 291.
95. Arthur Schopenhauer (1788—1860), German philosopher. — 289.
96. Desiderius Erasmus (1469—1536), Dutch Renaissance humanist, Catholic priest, social critic, teacher, and theologian — 287.
97. Friedrich Schiller (1759—1805),German author — 277.
98. Benedetto Croce (1866—1952), Italian idealist philosopher— 275.
99. Honoré de Balzac (1799—1850), French novelist and playwright — 271.
100. Friedrich Schelling (1775—1854), German philosopher — 270.