Why is it der Reformator?

Reformator ends in -or, and almost all nouns ending in -or are masculine: in a German dictionary, 93% of them take der.

All nouns ending in -or
Sense 1
der

Meaning

[1] person of church history that promotes the Reformation

[1] Person der Kirchengeschichte, die die Reformation befördert

Examples

[1] "The reformer saw two dangers in the writing schools ..."

[1] „Zwei Gefahren sah der Reformator in den Schreibschulen…“

Declension

1 Singular Plural
Nominativ der Reformator die Reformatoren
Genitiv des Reformators der Reformatoren
Dativ dem Reformator den Reformatoren
Akkusativ den Reformator die Reformatoren

Pronunciation

Dictionary entries include material from Wiktionary. Wiktionary