| Honorific Prefix: | Lt. Col. |
| Robert Smith-Dorrien | |
| Honorific Suffix: | JP |
| Birth Name: | Robert Algernon Smith |
| Birth Date: | 2 October 1814 |
| Death Date: | 8 October 1879 (aged 65) |
| Spouse: | Mary Anne Drever (married 1845) |
| Children: | 15 (including Thomas Smith-Dorrien and Horace Smith-Dorrien) |
| Parents: |
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| Relatives: | Augustus Smith (brother) |
Lieutenant Colonel Robert Algernon Smith-Dorrien (; 2 October 1814 – 8 October 1879)[1] was a British churchwarden and soldier.[2]
Robert Smith was born on 2 October 1814 to James Smith and Mary Isabella Pechell. He married Mary Anne Drever, a member of the Dorrien family, in 1845. He adopted his wife's maiden name and changed his surname by Royal Licence to Smith-Dorrien. Together they had 15 children, including Thomas Smith-Dorrien and Horace Smith-Dorrien.
He served as a Justice of the Peace. He was a lieutenant colonel, serving in the Hertfordshire Militia and also a captain in both the 3rd Light Dragoons and the 16th Lancers.
Smith-Dorrien was heavily involved in the restoration of the now Grade II* listed St Peter's Church in Berkhamsted, Hertfordshire, serving as the Churchwarden from 1868 until his death on 8 October 1879. Due to his work for the church building, a stained glass window by Charles Eamer Kempe was installed and dedicated in his honour, along with a plaque.
Smith-Dorrien's elder brother was Augustus Smith, Lord Proprietor of the Isles of Scilly from 1834 to 1872. Augustus Smith was succeeded as Lord Proprietor by Robert Smith-Dorrien's eldest son, Thomas Algernon Smith-Dorrien.