| Singular | Plural | |
|---|---|---|
| Nominativ | cassivellaunus, vercassivellaunus | cassivellauni |
| Genitiv | cassivellauni | cassivellaunorum |
| Dativ | cassivellauno, vercassivellauno | cassivellaunis |
| Akkusativ | cassivellaunom, cassivellaunum, vercassivellaunum | cassivellaunos |
| Ablativ | cassivellauno, vercassivellauno | cassivellaunis |
| Vokativ | cassivellaune | cassivellauni |