Iris foetidissima, the stinking iris, gladdon, Gladwin iris, roast-beef plant, or stinking gladwin, is a species of flowering plant in the family Iridaceae, found in open woodland, hedgebanks and on sea-cliffs.

Its natural range is Western Europe, including England (south of Durham) and also Ireland, and from France south and east to N. Africa, Italy and Greece.

It is one of two iris species native to Britain, the other being the yellow iris (Iris pseudacorus).

It has tufts of dark green leaves. Its flowers are usually of a dull, leaden-blue colour, or dull buff-yellow tinged with blue. The petals have delicate veining. It blooms between June and July, but the flowers only last a day or so.