I will be a historical painter.

1770–1853) Canadian banker businessman and politician
William Allan (classicist) (born 1970) Scottish classicist
William Allan (geneticist) (1881–1943) United States physician and geneticist
William Allan (painter) (1782–1850) Scottish historical painter
William Allan (UK politician) (1837–1903) Liberal Party politician in the United Kingdom
William Evan Allan (1899–2005) Australian military figure seeing service in WWI and WWII
William Fitz Allan Lord of Oswestry (1105–1160) a Norman noble.