1. Dmitry Lachinov, (1842–1902), Russia – mercury pump, economizer for electricity consumption, electrical insulation tester, optical dynamometer, photometer, elecrolyser
2. René Laënnec, (1781–1826), France – stethoscope
3. Lala Balhumal Lahuri, (c. 1842), Mughal India – seamless globe and celestial globe
4. Georges Lakhovsky, (1869–1942), Russia/U.S. – Multiple Wave Oscillator
5. Hedy Lamarr, (1913–2000), Austria and U.S. – Spread spectrum radio
6. Edwin H. Land, (1909–1991), U.S. – Polaroid polarizing filters and the Land Camera
7. Samuel P. Langley, (1834–1906), U.S. – bolometer
8. Irving Langmuir, (1851–1957), U.S. – gas filled incandescent light bulb, hydrogen welding
9. Lewis Latimer, (1848–1928), U.S. – Invented the modern day light bulb
10. Gustav de Laval, (1845–1913), Sweden – invented the milk separator and the milking machine
11. Semyon Lavochkin, (1900–1960), Russia – La-series aircraft, first operational surface-to-air missile S-25 Berkut
12. John Bennet Lawes, (1814–1900), UK – superphosphate or chemical fertilizer
13. Nikolai Lebedenko, Russia – Tsar Tank, the largest armored vehicle in history
14. Sergei Lebedev, (1874–1934), Russia – commercially viable synthetic rubber
15. Antoni van Leeuwenhoek, (1632–1723), Netherlands – development of the microscope
16. Jerome H. Lemelson, (1923–1997), U.S – Inventions in the fields in which he patented make possible, wholly or in part, innovations like automated warehouses, industrial robots, cordless telephones, fax machines, videocassette recorders, camcorders, and the magnetic tape drive used in Sony's Walkman tape players.
17. Jean-Joseph Etienne Lenoir, (1822–1900), Belgium – internal combustion engine, motorboat
18. R. G. LeTourneau, (1888–1969), U.S. – electric wheel, motor scraper, mobile oil drilling platform, bulldozer, cable control unit for scrapers
19. Willard Frank Libby, (1908–1980), U.S. – radiocarbon dating
20. Justus von Liebig, (1803–1873), Germany – nitrogen-based fertilizer
21. Otto Lilienthal, (1848–1896), Germany – hang glider
22. Frans Wilhelm Lindqvist, (1862–1931), Sweden – Kerosene stove operated by compressed air
23. Hans Lippershey, (1570–1619), Netherlands – telescope
24. Lisitsyn brothers, Ivan Fyodorovich and Nazar Fyodorovich, Russia – samovar (the first documented makers)
25. William Howard Livens, (1889–1964), UK – chemical warfare – Livens Projector.
26. Alexander Lodygin, (1847–1923), Russia – electrical filament, incandescent light bulb with tungsten filament
27. Mikhail Lomonosov, (1711–1765), Russia – night vision telescope, off-axis reflecting telescope, coaxial rotor, re-invented smalt (data by facebook/cnaonweb)
28. Yury Lomonosov, (1876–1952), Russia/United Kingdom – first successful mainline diesel locomotive
29. Aleksandr Loran, (1849 – after 1911), Russia – fire fighting foam, foam extinguisher
30. Oleg Losev, (1903–1942), Russia – light-emitting diode, crystadine
31. Archibald Low, (1882–1956), Britain – Pioneer of radio guidance systems
32. Auguste and Louis Lumière, France – Cinématographe
33. Gleb Lozino-Lozinskiy, (1909–2001), Russia – Buran (spacecraft), Spiral project
34. Ignacy Łukasiewicz, (1822–1882), Poland – modern kerosene lamp
35. Giovanni Luppis, (1813–1875), Austrian Empire (ethnical Italian) – self-propelled torpedo
36. Ali Kashmiri ibn Luqman, (fl.1589–1590), Mughal India – seamless globe and celestial globe
37. Arkhip Lyulka, (1908–1984), Russia – first double jet turbofan engine, other Soviet aircraft engines