William Clarke Wontner , was an English portrait painter steeped in Academic Classicism and Romantic.

Wontner was born in Stockwell, Surrey, the son of noted architect, designer and renderer William Hoff Wontner (1814–1881) and Catherine Smith.

William received his earliest art education from his father. Under his father's direction, Wontner worked with John William Godward (1861–1922), a noted exponent of what became known as Greco-Roman style, who was an acquaintance of the Wotner family. Godward was five years older than Wotner, and the pair became great friends.

Wontner began teaching at St Johns Wood Art School in around 1885 after he moved to Hamilton Garden Square. Wontner was a relatively minor painter who was part of the neo-classical movement in England, led by Alma-Tadema. His style favoured seductively languorous women against classical or oriental marbled backdrops.
His faithfully rendered fabrics draped over patently European models, somehow created an air of Orientalism. His work was exhibited at the Royal Academy from 1879, at the Society of British Artists and at the Royal Institute of Painters in Water Colours. When the Grosvenor Gallery closed in 1890, Wontner exhibited at the New Gallery.