William Barclay may refer to:
- William Barclay (jurist), Scottish jurist in the 16th and early 17th centuries
- William Barclay (writer)
- William Barclay (painter)
- William Barclay (theologian), 20th century theologian and writer of Bible commentaries
- William Barclay (politician), New York State Assemblyman
- William Barclay (UK politician), Northern Irish Senator