Subject (Latin: subiectus "lying beneath") may refer to:

• Hypokeimenon, or subiectum, in metaphysics, the "internal", non-objective being of a thing
  • Subject (philosophy), a being that has subjective experiences, subjective consciousness, or a relationship with another entity

• Subject (grammar), who or what a sentence or a clause is about
• Subject case or nominative case, one of the grammatical cases for a noun

• Subject (music), or 'theme'
• The melodic material presented first in a fugue
• Either of the two main groups of themes (first subject, second subject), in sonata form
• Subject (album), a 2003 album by Dwele
• Subjects (album), a 2021 album by Scale the Summit

• The individual, whether an adult person, a child or infant, or an animal, who is the subject of research.

• Subjects (programming), core elements in the subject-oriented programming paradigm
• Subject (access control)
• An element in the Resource Description Framework

• Subject (documents) (subject classification; subject indexing; subject searching)
• Subject term or index term, a descriptor of a document used in bibliographic records

• Commoner, an individual subjected to rule by an elite, e.g. in feudalism
• Subject in a modern constitutional monarchy, e.g. British subject
• Course (education), a unit of academic instruction
• Subject, a 2022 documentary about documentaries by Jennifer Tiexiera

• Subject matter (disambiguation)
• Subjective (disambiguation)