We almost always use revolutionary (versus revolutionist or revolutioner, etc.) to name (noun) or describe (adjective) someone who caused, led, supported, or was important to a revolution (major and fundamental change).
From the Corpus of Contemporary American English (COCA):
And here's a young girl on a horse who was a great revolutionary heroine, so you should by all means stop and see that one.
Date: 1994 (19940703); Title: Authors Remember American Women's Historical Landmarks; Source: NPR_Weekend.
Davies, Mark. 2008- The Corpus of Contemporary American English: 450 million words, 1990-present. Available online at http://corpus.byu.edu/coca/.
The Christian ministry has been located on the corridor for 10 years. "King was such a revolutionist," Thomas said. " That's what we're trying to do.
Date: 2000 (20000113); Publication information: CityLife Atlanta (Extra); Title: A stroll down MLK Drive;The road named for the civil rights leader tells a story as it meanders through town; Author: S.A. Reid, Staff; Source: Atlanta Journal Constitution.
Revolutionary appeared 7,877 times in the COCA, while revolutionist appeared 12 and revolutioner 0.