The phrase "most subaltern" refers to the highest ranking or most privileged individuals in a particular hierarchy, social structure, or organization. The primary antonyms for this phrase are those that describe individuals who are at the bottom of these same structures or hierarchies: the least privileged, most marginalized, and most oppressed members of society. Some possible antonyms to "most subaltern" might include terms such as elite, powerful, influential, or important. However, it is important to recognize that these antonyms do not quite capture the full opposite of "most subaltern," as they describe individuals who are not necessarily at the bottom of social structures but rather hold prominent positions within them.