| Type: | lead |
| Age Range: | 20 – 30 |
| Gender: | female |
| Voice Part: | mezzo |
| Vocal Range: | none |
| Dancing: | N/A |
| Name | Gender | Vocal Part | Age Range | Role Type |
| A Monk | male | bass | 50 – 80 | supporting |
| A Voice from Heaven | female | soprano | 20 – 60 | cameo |
| Count of Lerma | male | tenor | 21 – 45 | cameo |
| Countess of Aremberg | female | mute | cameo | |
| Don Carlo | male | tenor | 21 – 35 | lead |
| Elisabeth of Valois | female | soprano | 20 – 30 | lead |
| Flemish deputies, Inquisitors, Ladies and Gentlemen of the Spanish Court, the people, Pages, Guards, Monks, Soldiers | N/A | 10 – 80 | chorus | |
| Philip II | male | bass | 40 – 65 | lead |
| Rodrigo | male | baritone | 21 – 35 | lead |
| Royal Herald | male | tenor | cameo | |
| The Grand Inquisitor | male | bass | 35 – 60 | supporting |
| Tybalt | N/A | soprano | 10 – 19 | cameo |