| S.No. | The lightest in World | Description |
| 1 | The lightest boxing weight class held as part of the Boxing at the 1904 Summer Olympics programme |
Boxing at the 1904 Summer Olympics – Flyweight
|
| 2 | The lightest particle containing charm quarks | D mesons |
| 3 | The lightest alkane to have a flash point above 25 °C |
Nonane
|
| 4 | The lightest element of the halogen column of the periodic table |
Fluorine
|
| 5 | The lightest robot helicopter prototype |
Seiko Epson Micro flying robot
|
| 6 | The lightest and most abundant chemical element | hydrogen |
| 7 | The smallest and lightest of the world's loons | Red-throated Loon |
| 8 | The Lightest heavyweight champion | Robert James "Bob" Fitzsimmons (May 26, 1863 – October 22, 1917) |
| 9 | The lightest nuclides found naturally | niobium-93 and molybdenum-94 |
| 10 | The lightest metal and the least dense solid element | Lithium |
