Sir Alexander Dick, 3rd Baronet of Prestonfield PRCPE FRSE FSAScot (22 October 1703 – 10 November 1785) was a Scottish landowner and physician, who rose to be President of the Royal College of Physicians of Edinburgh.

He changed his surname to Dick on the death in 1746 of his elder brother William, when he inherited the baronetcy and Prestonfield.

[4] After qualifying as a physician, he set up in practice in Pembrokeshire prior to his inheritance.

He was made a Fellow of the Royal College of Physicians of Edinburgh in 1727 and elected President of the Society from 1756 to 1763.

He is mentioned in James Boswell's The Journal of a Tour to the Hebrides with Samuel Johnson (1785).