William O’Brien1 
He gained the rank of officer in the Indian Royal Horse Artillery.1
- [S21] L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 210. Hereinafter cited as The New Extinct Peerage.
Terence O’Brien1
- [S21] L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 210. Hereinafter cited as The New Extinct Peerage.
Margaret O’Brien1
Her married name became Martin.1
- [S21] L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 210. Hereinafter cited as The New Extinct Peerage.
James Martin1
He lived at Dublin, County Dublin, IrelandG.1
- [S21] L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 210. Hereinafter cited as The New Extinct Peerage.
Ellen O’Brien1
Her married name became Daniell.1
- [S21] L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 210. Hereinafter cited as The New Extinct Peerage.
Robert Daniell1
- [S21] L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 210. Hereinafter cited as The New Extinct Peerage.
Catto O’Brien1
- [S21] L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 210. Hereinafter cited as The New Extinct Peerage.
Anne O’Brien1
- [S21] L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 210. Hereinafter cited as The New Extinct Peerage.
Annie Clarke1 
From 8 August 1867, her married name became O’Brien.1 After her marriage, Annie Clarke was styled as Baroness O’Brien on 16 June 1900.
Children of Annie Clarke and Peter O’Brien, 1st and last Baron O’Brien
- James O’Brien1
- Annie Georgina O’Brien1
- Hon. Ellen Mary O’Brien1 d. 13 Oct 1930
- [S21] L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 210. Hereinafter cited as The New Extinct Peerage.
- [S47] BIFR1976 See link for full details for this source. Hereinafter cited as. [S47]
- [S47] BIFR1976. [S47]
Annie Stacy Lloyd1 
From 1880, her married name became Clarke.1
Children of Annie Stacy Lloyd and Lt.-Col. Sir Marshal James Clarke
- Elizabeth Clarke1 b. 17 Jun 1885, d. 26 Jul 1952
- Admiral Sir Marshal Llewelyn Clarke+1 b. 9 May 1887, d. 8 Apr 1959
- Brian Lloyd Clarke1 b. 30 Sep 1888, d. 19 Apr 1915