Sir Charles Lucas (1613 — 28 August 1648) was a member of the landed gentry from Essex. A Royalist cavalry leader during the First English Civil War, in March 1646 he swore not to fight against Parliament again, but broke this promise when the Second English Civil War began in 1648. Lucas was executed following the Siege of Colchester in August 1648, and became a Royalist martyr after the 1660 Stuart Restoration.

Royalist statesman and historian Edward Hyde, 1st Earl of Clarendon, described Lucas as "rough, proud, uncultivated and morose", but "a gallant man to look upon and follow".

Charles Lucas was born in Colchester, Essex in 1613, sixth child and third son of Sir Thomas Lucas (1573–1625) and his wife Elizabeth (died 1647). His eldest brother Thomas (1598–1649) was technically illegitimate, and so the second brother John (1606–1671) inherited the family estates.

Lucas also had five sisters, Mary (1608–1646), wife of Sir Peter Killigrew (1593–1668) with whom she had a son, Anne (1614–?), Elizabeth (1612–1691), who married Sir William Walter (1604–1675), and Catherine (1605–1702), wife of Sir Edmund Pye (1607–1673). His youngest sister Margaret (1623–1673), was a prolific author and scientist who in 1645 married William Cavendish, 1st Duke of Newcastle (1593–1676), Royalist commander in Northern England from 1642 to 1644.

As a young man, Lucas served under his brother John in the Eighty Years War, and during the 1639 to 1640 Bishops' Wars commanded a troop of cavalry in the army of Charles I, being knighted in 1639. When the First English Civil War began in August 1642, Lucas joined the Royalist army, and was wounded at the Battle of Powick Bridge, the first major engagement of the conflict.

Early in 1643, Lucas raised a regiment of horse, with which he defeated Middleton at Padbury on 1 July. In January 1644, he commanded the forces attacking Nottingham, and soon afterwards, on the recommendation of Prince Rupert, he was made lieutenant-general of the Duke of Newcastle's Northern army. When Newcastle was shut up in York, Lucas and the cavalry remained in the open country, and when Rupert's relieving army crossed the hills into Yorkshire he was quickly joined by Newcastle's squadrons.

At Marston Moor in July 1644, Lucas swept Sir Thomas Fairfax's horse from the field, but the battle was a decisive Parliamentarian victory and he was captured during the fighting. Exchanged for Parliamentary prisoners during the winter, in December 1645 he defended Berkeley Castle against forces led by Thomas Rainsborough. The garrison surrendered after being granted free passage to the nearest Royalist territory, and Lucas became lieutenant-general of the remnants of the Royalist cavalry. In March 1646, he was captured once again at Stow-on-the-Wold, the last major battle of the First Civil War.

Lucas was released after promising not to bear arms against Parliament again, and in March 1648 compounded for the return of his estates after swearing an oath of loyalty. When the Second English Civil War began in May 1648, he ignored both agreements and took a prominent part in the seizure of Colchester; following a three-month siege, the town surrendered on 28 August 1648.