O'brien Marriage Records: Groom Firstnames
- David (26)
- David John (1)
- David W (1)
- Declan (2)
- Denis (3)
- Dennis (30)
- Dennis Durfey (1)
- Dennis Patrick (1)
- Dennis T (1)
- Derek (1)
- Dermot (2)
- Desmond (4)
- Donald (19)
- Donald Joseph (1)
- Donald Robert (1)
- Donn (1)
- Douglas (1)
- Duken (1)