William Arthur Sibly JP (14 May 1882 – 20 September 1959), also known by his initials W. A. S., was an English headmaster, activist, and writer.

His early years as headmaster were challenging, especially during World War I, but he managed to keep the school running smoothly despite numerous difficulties.

He oversaw the construction of several new buildings, including the Berryfield, the Library, the Assembly Hall, and the Memorial Chapel Tower and Spire, among others.

Despite this change, he continued to work with the council, contributing significantly to the school's ongoing development.

He contributed a paper titled "The Work Done at Wycliffe College", highlighting vegetarian practices at the school.

[4] In 1926, he presided over a session at the London Congress, where he discussed the implementation of a vegetarian diet at Wycliffe and its approval by the New Health Society.

[4] Sibly hosted and largely organised the 11th World Vegetarian Congress in the same year at Wycliffe, where he was re-elected as IVU President.

[4] During his presidency, Sibly attended the 1950 Congress in the Netherlands, where he delivered a lantern lecture titled "A Vegetarian Wanders Around the Commonwealth", focusing on Australasia.

His leadership was marked by a vision of vegetarianism as a hope for the future of humanity, a sentiment he expressed in his opening remarks at the Congress.

[4] Upon retiring from Wycliffe in 1945, Sibly embarked on extensive travels, visiting countries such as South Africa, India, Canada, New Zealand, Australia, Malaya, Kenya, the Middle East, West Africa, the United States, the West Indies, and South America.

[4] In addition to his work with the IVU and the Vegetarian Society, Sibly was actively involved in public life.

[12] Sibly's death marked the end of an era for the IVU, but his contributions to the vegetarian movement were considered to have a lasting impact.