George Lesley was created a Lord of Parliament in 1445 as Lord Lesley of Leven, and had all his lands united into the barony of Ballinbreich. He was advanced to the title of Earl of Rothes sometime prior to 1458. George, the 4th Earl, died in mysterious circumstances at Dieppe, along with the Earl of Cassillis and two others, returning from the wedding of Mary, Queen of Scots to the Dauphin in 1558.

Thereafter, the Lesleys abandoned politics for a time, for the less hazardous career of professional soldiery. Lesleys fought in Germany, France, Sweden and the Baltic. Perhaps the most famous of the Lesley mercenaries was Alexander Leslie, who was recalled from the Continent to take command of the Army of the Covenant, and was later raised to the peerage as the Earl of Leven. David Lesley, of the Rothes family, was also a Covenanter commander. He was routed by Cromwell' s troops at Dunbar in 1650 and imprisoned in the Tower of London until the Restoration in 1660, being created Lord Newark in the following year. The 7th Earl of Rothes was created a duke in 1680 by Charles II. He was a great favourite of the king and one of the most distinguished statesmen of his time. He was made a Lord of Session and President of the Council. The dukedom died with him as he left no male heir, but under the terms of an earlier charter, the earldom could pass through the female line, and thus the title was preserved.

The 9th Earl was Vice Admiral of Scotland and governor of Stirling Castle. He was a supporter of the Hanoverians, and in 1715 he commanded a regiment of cavalry at the Battle of Sheriffmuir. He sold much of the Rothes estates, although the magnificent Leslie House near Fife remained the seat of the earls until 1926. Leslie Castle in Aberdeenshire has also been fully restored in recent years by David Lesley, a prominent local architect. The use of the name (male - Leslie, female - Lesley) as a forename is of fairly recent origin.