Keep in mind 'detractor' may imply that criticism is unfair or not completely justified. The writer's detractors failed to recognize the historical context of his work.
Pro Tip 2/3
Beyond Criticism
'Detractor' goes beyond 'critic' by suggesting active efforts to discredit. Even the software's detractors couldn't deny its innovative features.
Pro Tip 3/3
Intensified Opposition
A 'detractor' often expresses their criticism repeatedly, not just once. As a leading scientist, she has her detractors who constantly challenge her theories.