perfectionist
n. B2 Upper Intermediate US //pɝˈfɛkʃənəst// UK //pəfˈɛkʃənˌɪst// per·fec·tion·ist
n. a person who believes that everything must be perfect. They often spend a lot of time trying to fix small mistakes.
n. a person who demands that everything be perfect or as close to perfect as possible. Often used to describe someone with an obsessive concern for detail and quality.
He is a perfectionist and never leaves his desk until everything is perfect.
The project was delayed because the lead designer was a perfectionist who refused to approve the final layout until every color was exactly right.
While a perfectionist's attention to detail can lead to exceptional results, it often comes at the cost of efficiency, as they spend disproportionate amounts of time on minor aesthetic adjustments.
From perfection + -ist.