Charles Douglas, 6th Marquess of Queensberry, KT (March 1777 – 3 December 1837) was a Scottish peer.
Douglas was the first son and heir of Sir William Douglas, Bt, and his wife, Grace, née Johnstone. He inherited his father's baronetcy in 1783. On 13 August 1803, he married Lady Caroline Scott (1774–1854), the third daughter of Henry Scott, 3rd Duke of Buccleuch; they had eight daughters.
In 1810, he succeeded his fourth cousin once removed, William Douglas, 4th Duke of Queensberry, as Marquess of Queensberry. From 1812 to 1832, he was a representative peer for Scotland, was made a Knight of the Thistle in 1821, and created Baron Solway, of Kinmount, in the County of Dumfries, in 1833, which granted him an automatic seat in the House of Lords.
On his death without male heirs in 1837, the marquessate and baronetcy passed to his brother, and the barony became extinct.
| Honorary titles | ||
|---|---|---|
| Preceded by The Duke of Buccleuch |
Lord Lieutenant of Dumfries 1819–1837 |
Succeeded by The Marquess of Queensberry |
| Baronetage of Nova Scotia | ||
| Preceded by William Douglas |
Baronet (of Kelhead) 1783–1837 |
Succeeded by John Douglas |
| Peerage of Scotland | ||
| Preceded by William Douglas |
Marquess of Queensberry 1810–1837 |
Succeeded by John Douglas |
| Peerage of the United Kingdom | ||
| New title | Baron Solway 1833–1837 |
Extinct |