The title of Earl of Wigtown (or Wigton or Wigtoun) was created twice in the Peerage of Scotland

Peerage of Scotland

The Peerage of Scotland is the division of the British Peerage for those peers created in the Kingdom of Scotland before 1707. With that year's Act of Union, the Kingdom of Scotland and the Kingdom of England were combined into the Kingdom of Great Britain, and a new Peerage of Great Britain was...

. The first creation was in 1341, and was surrendered in 1372, when the second earl sold the earldom and territory to Archibald the Grim , Lord of Galloway. The transfer was confirmed by Robert III

Robert III of Scotland

Robert III was King of Scots from 1390 to his death. His given name was John Stewart, and he was known primarily as the Earl of Carrick before ascending the throne at age 53...

 later in the same year The earls of Douglas held the earldom of Wigtown for the next hundred years, until the attainder

Attainder

In English criminal law, attainder or attinctura is the metaphorical 'stain' or 'corruption of blood' which arises from being condemned for a serious capital crime . It entails losing not only one's property and hereditary titles, but typically also the right to pass them on to one's heirs...

 of the 9th Earl of Douglas

James Douglas, 9th Earl of Douglas

James Douglas, 9th Earl of Douglas, 3rd Earl of Avondale KG was a Scottish nobleman, last of the 'Black' earls of Douglas. He was a twin, the older by a few minutes, the younger was Archibald Douglas, Earl of Moray....

 in 1455.

The second creation was in 1606, surviving until the death of the 7th earl in 1747, when it became dormant (or extinct?). The earls of the second creation bore the subsidiary titles of Lord Fleming and Cumbernauld (1606) and of Lord Fleming (1451, Peerage of Scotland, extinct 1747).

Earls of Wigtown, First Creation (1341)

• Malcolm Fleming, 1st Earl of Wigtown (d. c. 1363)
• Thomas Fleming, 2nd Earl of Wigtown (d. x 1382), title surrendered 1372

Lords Fleming (1451)

• Robert Fleming, 1st Lord Fleming (d. 1494)
• John Fleming, 2nd Lord Fleming (d.1524)
• Malcolm Fleming, 3rd Lord Fleming
  Malcolm Fleming, 3rd Lord Fleming
  Malcolm Fleming, 3rd Lord Fleming , was Lord Chamberlain of Scotland to King James V, from 1524.He was the son and heir of John Fleming, 2nd Lord Fleming, who was killed in a feud with the Tweedie of Drumelzier family in 1524....
  
   (c.1494–1547)
• James Fleming, 4th Lord Fleming
  James Fleming, 4th Lord Fleming
  James Fleming, 4th Lord Fleming was Lord Chamberlain of Scotland.-Life:He was the eldest son of Malcolm Fleming, 3rd Lord Fleming, lord high chamberlain, by his wife Johanna or Jonet Stewart, natural daughter of James IV....
  
   (b.1538–1558)
• John Fleming, 5th Lord Fleming
  John Fleming, 5th Lord Fleming
  -Life:He was the son of Malcolm Fleming, 3rd Lord Fleming, lord high chamberlain, by his wife Johanna or Jonet Stewart, natural daughter of James IV.He succeeded his brother James Fleming, 4th Lord Fleming....
  
   (d. 1572)
• John Fleming, 6th or 7th Lord Fleming (1567–1619) became Earl of Wigtown in 1606

Earls of Wigtown, Second Creation (1606)

• John Fleming, 1st Earl of Wigtown (1567–1619)
• John Fleming, 2nd Earl of Wigtown (1589–1650)
• John Fleming, 3rd Earl of Wigtown (d.1665)
• John Fleming, 4th Earl of Wigtown (d.1668)
• William Fleming, 5th Earl of Wigtown (d.1681)
• John Fleming, 6th Earl of Wigtown (1673–1744)
• Charles Fleming, 7th Earl of Wigtown (1675–1747)

Sources

• Fraser, Sir William
  William Fraser (historian)
  Sir William Fraser, KCB, was a solicitor and notable expert in ancient Scottish history, palaeography, and genealogy....
  
  The Douglas Book IV vols Edinburgh 1885.