| Name | Children | Media (from resource) | Traits |
|---|---|---|---|
| Xestospongia Laubenfels 1932 | 1 | 0 | 0 |
| Xestospongia testudinaria (Lamarck 1815) | 0 | 0 | 1 |
| Xiphias | 1 | 0 | 0 |
| Xiphias gladius Linnaeus 1758 (Espadon) | 0 | 0 | 1 |
| Xiphiidae | 1 | 0 | 0 |
| Xylaria | 1 | 0 | 0 |
| Xylaria multiplex (Kunze) Fr. 1851 | 0 | 0 | 1 |
| Xylariaceae | 3 | 0 | 0 |
| Xylosma | 1 | 0 | 0 |
| Xylosma simulans A. C. Sm. | 0 | 0 | 1 |
| Yongeichthys | 1 | 0 | 0 |
| Yongeichthys criniger (Valenciennes 1837) | 0 | 0 | 1 |
| Zafra A. Adams 1860 | 2 | 0 | 0 |
| Zafra atrata (Gould 1860) | 0 | 0 | 1 |
| Zafra pumila (Dunker 1858) | 0 | 0 | 1 |
