Lewellyn is a rare boys' name that was most common in the 1920s and has all but disappeared.
Lewellyn is predominantly a boy name. It last appears in U.S. records in 1962. Lewellyn was first reported in SSA data in 1912 and peaked in 1929 (17 births).
| Year | U.S. births | U.S. + territories | ♀ Rank | ♂ Rank |
|---|---|---|---|---|
| 1962 | 5 | — | — | #4,396 |
| 1961 | 5 | — | — | #4,411 |
| 1958 | 7 | — | — | #3,448 |
| 1956 | 9 | — | — | #2,894 |
| 1954 | 5 | — | — | #4,141 |
| 1952 | 7 | — | — | #3,261 |
| 1951 | 5 | — | — | #4,031 |
| 1949 | 6 | — | — | #3,545 |
| 1948 | 6 | — | — | #3,525 |
| 1945 | 6 | — | — | #3,191 |
| 1944 | 14 | — | — | #1,935 |
| 1943 | 5 | — | — | #3,832 |
| 1940 | 12 | — | #3,700 | #3,736 |
| 1939 | 18 | — | #4,613 | #2,013 |
| 1937 | 5 | — | — | #3,825 |
| 1936 | 6 | — | — | #3,379 |
| 1935 | 8 | — | — | #2,844 |
| 1934 | 13 | — | #4,663 | #2,857 |
| 1933 | 13 | — | #4,004 | #3,165 |
| 1931 | 7 | — | — | #3,279 |
| 1930 | 12 | — | — | #2,385 |
| 1929 | 22 | — | #4,969 | #1,899 |
| 1928 | 9 | — | — | #2,972 |
| 1927 | 5 | — | — | #4,535 |
| 1926 | 11 | — | — | #2,662 |
| 1925 | 10 | — | — | #2,858 |
| 1924 | 6 | — | — | #4,143 |
| 1923 | 7 | — | — | #3,675 |
| 1922 | 8 | — | — | #3,418 |
| 1921 | 15 | — | — | #2,220 |
| 1920 | 9 | — | — | #3,096 |
| 1919 | 9 | — | — | #3,021 |
| 1918 | 8 | — | — | #3,262 |
| 1917 | 12 | — | #4,977 | #3,421 |
| 1916 | 10 | — | — | #2,653 |
| 1915 | 5 | — | — | #4,148 |
| 1914 | 5 | — | — | #3,543 |
| 1913 | 8 | — | — | #2,184 |
| 1912 | 6 | — | — | #2,443 |