William Lawson (2 June 1774 – 16 June 1850) was an explorer of New South Wales, Australia, who co-discovered a passage inland through the Blue Mountains from Sydney.

Lawson was born in Finchley, Middlesex, England, son of Scottish parents who had lived at Kirkpatrick. Lawson arrived in Sydney as an ensign with the New South Wales Corps in November 1800, soon being posted to Norfolk Island.

Shortly after 1808, Lawson was appointed aide-de-camp to George Johnston and was granted 500 acres (2 km²) at Prospect, which he named Veteran Hall. He built a 40-room mansion there.

In 1813 Lawson, with Gregory Blaxland and William Wentworth, led an expedition westwards from Sydney to cross the Blue Mountains. They departed on 11 May 1813 with four servants, five dogs and four horses. The route they traversed is, with some slight variations, still the one used by travellers today. On 31 May 1813 they reached Mount Blaxland from where they could see the plains to the west. Beyond the mountains the explorers found a great expanse of open country, which they surveyed.

Lawson was rewarded with a grant of 1,000 acres (4 km²) of land, he subsequently became one of the largest land holders in Australia. He was made a magistrate and was appointed commandant at Newcastle. In 1819 Governor Lachlan Macquarie established a new settlement, Bathurst, in this new country, and appointed Lawson as commander of the Bathurst settlement, a position he held until 1823. From Bathurst, Lawson explored as far north as Mudgee.

After leaving the army, Lawson was a member of the New South Wales Legislative Council from 1843 to 1848. He died at Vereran Hall on 16 June 1850, he had married and left descendants. The town of Lawson in the Blue Mountains is named for him.

After Lawson's death, Veteran Hall eventually became acquired by the Metropolitan Water Board. The house was demolished in 1926 and most of the property is submerged by the waters of Prospect reservoir.

In 1963 Lawson was honoured, together with Blaxland and Wentworth, on a postage stamp issued by Australia Post depicting the Blue Mountains crossing.