| Surname | Country | State | County or Province | From | To | Member |
|---|---|---|---|---|---|---|
| Labuda | Prussia | Lauenberg | 1840 | ? | T004-1 | |
| Lacoste | France | Périgord | Dordogne | 1680 | 1728 | J009-1 |
| Lafarge | France | Périgord | Dordogne | 1700 | 1737 | J009-1 |
| Lafaysse | France | Périgord | Dordogne | 1660 | 1844 | J009-1 |
| Lagiorina | Italy | Basilicata | Potenza | 1875 | 1890 | J009-1 |
| Lagiorina | USA | Illinois | 1890 | 1955 | J009-1 | |
| Lahey | Ireland | L008-1 | ||||
| Lahey | USA | Illinois | L008-1 | |||
| Lahr | Germany | F006-1 | ||||
| Lahr | USA | F006-1 | ||||
| Laietta | France | Provence-Alpes-Côte-d'Azur | Alpes-Maritimes | 1680 | 1760 | J009-1 |
| Lamb | USA | New York | abt 1780 | abt 1840 | D005-1 | |
| Landen | K002-1 | |||||
| Landon | K002-1 | |||||
| Lange | Poland | Wabrzezno | 1700 | 1920 | S017-1 | |
| Langer | W008-1 | |||||
| Lapham | A010-1 | |||||
| Lapouge | France | Périgord | Dordogne | 1650 | 1742 | J009-1 |
| Lassaigne/Lassagnie | France | Périgord | Dordogne | 1753 | 1813 | J009-1 |
| Latham | A010-1 | |||||
| Latimer | USA | Missouri | S034-2 | |||
| Laucius | Lithuania | pre 1909 | L014-1 | |||
| Laucius | USA | Illinois | Cook County | 1909 | 1940 | L014-1 |
| Laugeri | France | Provence-Alpes-Côte-d'Azur | Alpes-Maritimes | 1684 | 1734 | J009-1 |
| Laughlin | USA | New York | Steuben County | 1840 | 1930 | H012-1 |
| Leach | USA | Virginia (now WV) | Wood County | 1825 | present | O001-1 |
| Leach | USA | Virginia | Fauquier County | 1785 | 1825 | O001-1 |
| Leach | USA | Indiana | Warren County | 1830 | 1900 | S009-1 |
| Leach | USA | Ohio | Jackson County | 1818 | present | O001-1 |
| Leach | USA | Iowa | Black Hawk County | 1818 | present | O001-1 |
| Leach | USA | Iowa | Jasper County | 1818 | present | O001-1 |
| Leach | USA | Iowa | Polk County | 1818 | present | O001-1 |
| Leandri | Italy | Tuscany | Lucca | J009-1 | ||
| Ledwick | Germany | C002-1 | ||||
| Ledwick | Ireland | C002-1 | ||||
| Ledwitch | Germany | C002-1 | ||||
| Ledwitch | Ireland | C002-1 | ||||
| Lee | USA | Ohio | Marion County | 1850 | 1930 | H012-1 |
| Lee | USA | Virginia | 1762 | present | S029-1 | |
| Leis(s) | Germany | Bavaria | 1820 | 1850 | N001-1 | |
| Leis(s) | USA | Ohio | Montgomery County | 1845 | 1856 | N001-1 |
| Leis(s) | USA | Minnesota | Scott County | 1856 | 1900 | N001-1 |
| Leitner | Austria | Burgenland | 1830 | present | S005-1 | |
| Leksic | Croatia | GubisnoPolje | 1888 | 1906 | R003-1 | |
| Leksic | USA | Illinois | Cook County | 1906 | 1915 | R003-1 |
| Leksic | USA | Wisconsin | Kenosha County | 1915 | R003-1 | |
| Leksich | R003-1 | |||||
| Leotardi | France | Provence-Alpes-Côte-d'Azur | Alpes-Maritimes | 1670 | 1778 | J009-1 |
| LePrince | France | B026-1 | ||||
| Lestable | France | Périgord | Dordogne | 1600 | 1726 | J009-1 |
| Lewis | A010-1 | |||||
| Lieber | Germany | Hannover | 1778 | 1829 | P003-1 | |
| Lienesch | Germany | Ankum | Hannover | 1500s | present | M011-1 |
| Lienesch | USA | Illinois | St. Clair County | 1839 | present | M011-1 |
| Lignac | France | Périgord | Dordogne | 1680 | 1888 | J009-1 |
| Lilly | A010-1 | |||||
| Lilly | England | Bristol County | 1728 | 1754 | T007-1 | |
| Lilly | USA | Maryland | Frederick County | 1757 | 1894 | T007-1 |
| Lind | Sweden | Varmland | 1871 | present | O001-1 | |
| Lind | USA | Minnesota | Lake County | 1871 | present | O001-1 |
| Lind | USA | Minnesota | St. Louis County | 1871 | present | O001-1 |
| Lind | USA | Minnesota | Hennepin County | 1871 | present | O001-1 |
| Lindberg | Sweden | K019-1 | ||||
| Lindsay | Northern Ireland | 1650 | 1780 | D013-1 | ||
| Lindsay | USA | Pennsylvania | Franklin County | 1730 | 1830 | D013-1 |
| Lindsay | USA | Illinois | Peoria County | 1830 | 1880 | D013-1 |
| Lindsay | USA | Nebraska | Knox County | 1880 | Present | D013-1 |
| Lingeman | USA | Michigan | M026-1 | |||
| Lingemann | USA | Michigan | M026-1 | |||
| Lipp | Germany | Wurttemberg | 1785 | 1860 | T009-1 | |
| Lipp | USA | Illinois | Dekalb County | 1890 | 1970 | T009-1 |
| Lisewski | Germany/Poland | Debro Parish | Poznan | 1858 | 1888 | R003-1 |
| Lisewski | USA | Illinois | LaSalle County | 1888 | 1912 | R003-1 |
| Lisewski | USA | Illinois | Cook County | 1912 | 1942 | R003-1 |
| Lockwood | USA | New York | Westchester County | 1700 | 1819 | S009-1 |
| Lockwood | USA | Indiana | Gibson County | 1819 | present | S009-1 |
| Logbottom | USA | 1800 | present | C001-1 | ||
| Lombard | France | Provence-Alpes-Côte-d'Azur | Alpes-Maritimes | 1600 | 1661 | J009-1 |
| Losee | USA | New York | Westchestor County | 1700 | 1780 | S009-1 |
| Lowry | USA | Georgia | Franklin County | 1785 | 1825 | K021-1 |
| Lufkin | USA | Maine | Oxford County | L006-1 | ||
| Lukosius | Lithuania | Silale | 1865 | ? | T004-2 | |
| Lundgren | Sweden | 1841 | present | O001-1 | ||
| Lundgren | USA | Michigan | Delta County | 1841 | present | O001-1 |
| Lundgren | USA | Wisconsin | Marinette County | 1841 | present | O001-1 |
| Lyon | USA | Tennessee | Washington County | 1785 | 1840 | K021-1 |
| Lyon | USA | Virginia | Scott County | 1830 | 1950 | K021-1 |
| Lyons | Ireland | County Mayo | 1840 | present | B032-1 |