Robert Porrett Collier, 1st Baron Monkswell, PC QC (21 June 1817 – 27 October 1886) was an English lawyer, politician and judge.

Already a politician, he made some speeches at Launceston in 1841 with a view to contesting the borough in the Liberal interest, but did not go to the poll, and he was an active member of the Anti-Corn Law League and addressed the meetings in Covent Garden Theatre.

His first important success was a brilliant defence of some Brazilian pirates at Exeter in July 1845; the prisoners were, however, condemned to death, and the judge (Baron Platt) refused to reserve a point of law on which Collier insisted.

He was appointed recorder of Penzance, and in 1852 he was returned to Parliament for Plymouth, in the Liberal interest, and retained the seat till he became a member of the Judicial Committee of the Privy Council.

After a keen rivalry with Montague Edward Smith, afterwards a judge, for the foremost place, he obtained the lead of the circuit and kept it for many years[1] In 1859, he was appointed counsel to the Admiralty and Judge-Advocate of the Fleet.

[2] It was his opinion in favour of detaining the Confederate rams in the Mersey that Mr Adams, the American minister, submitted in 1862 to Lord John Russell, and, although too late to prevent the CSS Alabama going to sea, it was afterwards adopted by the law officers of the Crown.

He filled the office, however, with success until the Liberal government resigned in 1866, and in December 1868 he became Attorney-General, and in the next year he had the conduct of the Bankruptcy Bill in the House of Commons.

[1] In 1871, to enable the Judicial Committee of the Privy Council, to overtake its arrears of colonial appeals, an act was passed providing for four paid judgeships, two of which were to be held by judges or ex-judges of the English bench.

Collier held this post until his death, and the task of giving literary shape to the judgments of the Privy Council was frequently committed to him.

[1] He published a treatise on the Railways Clauses Acts, 1845; another on Mines in 1849; a letter to Lord John Russell on the 'Reform of the Common Law Courts,' 1851, 2nd ed.

When solicitor-general he painted in St. James's Park, and he exhibited frequently at the Royal Academy and Grosvenor Gallery, especially pictures of the neighbourhood of Rosenlaui, Switzerland, where he spent many vacations.

[1][9] His grave lies on the east side of the main path from the north entrance to the central colonnades in Brompton Cemetery in London.