William Patrick Maley (25 April 1868 – 2 April 1958) was an Irish-born Scottish international football player and manager. He was the first manager of Celtic Football Club, and one of the most successful managers in Scottish football history. During his managerial tenure, Maley led Celtic to 30 major trophies (16 league championships and 14 Scottish Cups) in 43 consecutive years as manager. He is attributed to have coined the famous Celtic motto 'It is not his creed nor his nationality which counts; it's the man himself.'

Maley was born in Newry Barracks, County Down, Ireland, the third son of Thomas Maley and Mary Montgomery. Thomas came from Ennis, County Clare, while Mary had been born in Canada to Scottish parents. At the time of his son's birth, Thomas was stationed in Newry as a sergeant in the 21st (Royal North British Fusilier) Regiment of Foot. In 1869, Thomas took honourable discharge from the British Army and the family moved to Scotland, settling in Cathcart – at that time a village just south of Glasgow.

Maley left school at the age of 13 and worked for a few years in the printworks of Miller, Higginbotham & Co., and then at the Telephone Company of Glasgow. Eventually he was offered the opportunity to train as a chartered accountant with Smith and Wilson, a Glasgow accountancy firm. As a young man, Maley was much more involved in athletics than in football, although he had played a few games for Cathcart Hazelbank Juniors in 1886 and had played with Third Lanark from later that year.

On a visit to Cathcart in December 1887 to invite Tom Maley to join Celtic, Brother Walfrid and the rest of the Celtic deputation met Willie Maley and they casually invited him to also play for the club. In 1888, he was signed by the fledgling Celtic and became one of the club's first players as a midfielder. In 1896, he made a single appearance for Manchester City in a Second Division match against Loughborough.

Due to his Scottish maternal grandparents and having lived in Scotland since the age of one, Maley played for the Scotland national team, earning two caps in 1893 against England and Ireland. Maley represented the Scottish League twice.

In 1897, the board of Celtic directors appointed Willie Maley, at just 29 years of age, as Secretary-Manager – the first manager – of Celtic. He won the Scottish League championship for the club in his first full season as manager. Maley never worked with his players in training, he watched games from the directors' box and never indulged in team talks or spoke to his players at half-time or post-match.^{[citation needed]} Maley would not even announce the team: players learned if they were in or out through reading the line-up in the newspaper.^{[citation needed]}

Celtic had been a buying club in their opening decade, spending heavily to bring professionals to the club. Maley decided to scrap that and rely almost entirely on recruiting youngsters fresh from junior football.

Maley created a young team who won six consecutive league titles in a row between 1905 and 1910 and won the first Scottish League and Scottish Cup doubles. They were the best team in Glasgow, and the six-in-a-row record remained unbroken until the 1960s. As his six-in-a-row team began to age, Maley set about the task of building a younger team. This younger side, which included Patsy Gallacher and the apparently 'ageless' Jimmy McMenemy, won four league titles in succession between 1914 and 1917. They also set a UK record for an unbeaten run in professional football, 62 games (49 won, 13 drawn) from 13 November 1915 until 21 April 1917, which stood until it was broken by Brendan Rodgers' Celtic in November 2017.