| Name | Relationship with Natalie Seiwell | Civil | Canon |
| 31st great-grandfather | XXXIII | 33 |
| Clavering, John Fitzrichard | 26th great-granduncle | XXX | 29 |
| 29th great-granduncle | XXXIII | 32 |
| Clavering, Richard Fitzeustace Fitznigel | 27th great-grandfather | XXIX | 29 |
| 30th great-grandfather | XXXII | 32 |
| Clemence | 27th great-grandmother | XXIX | 29 |
| Clement, Agnes | 26th great-grandmother | XXVIII | 28 |
| Clements, Margery | 24th great-grandmother | XXVI | 26 |
| Clemmons, Margaret | Wife of the 2nd cousin 6 times removed | | |
| Clermont, Adelaide Roucy | 31st great-grandmother | XXXIII | 33 |
| 32nd great-grandmother | XXXIV | 34 |
| Clermont, Adeliza Roucy | 31st great-grandaunt | XXXV | 34 |
| 32nd great-grandaunt | XXXVI | 35 |
| Clermont, Bouduin | 34th great-grandfather | XXXVI | 36 |
| 35th great-grandfather | XXXVII | 37 |
| Clermont, Ermengardis | 33rd great-grandmother | XXXV | 35 |
| 34th great-grandmother | XXXVI | 36 |
| Clermont, Ermentrude Roucy | 31st great-grandaunt | XXXV | 34 |
| 32nd great-grandaunt | XXXVI | 35 |
| Clermont, Hugh Clermont | 32nd great-grandfather | XXXIV | 34 |
| 33rd great-grandfather | XXXV | 35 |
| Clermont, Renald II Roucy | 31st great-granduncle | XXXV | 34 |
| 32nd great-granduncle | XXXVI | 35 |
| Clermont, Renaud | 33rd great-grandfather | XXXV | 35 |
| 34th great-grandfather | XXXVI | 36 |
| Clifton, Mary Morton | 12th great-grandmother | XIV | 14 |
| 13th great-grandmother | XV | 15 |
| Clifton, Richard | 13th great-grandfather | XV | 15 |
| 14th great-grandfather | XVI | 16 |
| Cloughe, Susanna | 13th great-grandmother | XV | 15 |
| Coezou, Rivelin | 33rd great-grandfather | XXXV | 35 |
| 36th great-grandfather | XXXVIII | 38 |
| Coezou, Salome | 32nd great-grandmother | XXXIV | 34 |
| 35th great-grandmother | XXXVII | 37 |
| Coleman, James | Husband of the 5th cousin 3 times removed | | |
| Colhan, Fergus | 24th great-grandfather | XXVI | 26 |
| 25th great-grandfather | XXVII | 27 |
| 26th great-grandfather | XXVIII | 28 |
| 28th great-grandfather | XXX | 30 |
| Colhan, Marjorie Or Margaret | 23rd great-grandmother | XXV | 25 |
| 24th great-grandmother | XXVI | 26 |
| 25th great-grandmother | XXVII | 27 |
| 27th great-grandmother | XXIX | 29 |
| Combs, Abraham Willis | 9th great-granduncle | XIII | 12 |
| 10th great-granduncle | XIV | 13 |
| Combs, Ann Richardson | 6th great-grandaunt | X | 9 |
| 7th great-grandaunt | XI | 10 |
| Combs, Archdale Willis | 9th great-grandfather | XI | 11 |
| 10th great-grandfather | XII | 12 |
| Combs, Benjamin Combs | 3rd great-grandfather | V | 5 |