Of an actor, or a character in a drama, poem, novel, etc.: appearing only in the protasis (protasis, n. 1).

Of an actor's part, offering abundant opportunity for skill, display, etc.; of speeches, etc., impressive, effective.

Tragic; of a tragic demeanour.

In Theatrical phr.: sober, serious; relating or pertaining to the representation of sombre or tragic parts; as heavy villain, heavy business.

That takes or performs the leading role; that is the most prominent or important; principal. Cf. star, v. 6a.

Characteristic of or resembling Polonius, the elderly and sententious courtier in Shakespeare's Hamlet; given to using moralistic aphorisms…

That provides support for a main part, performer, performance, or entertainment; not heading the bill; secondary.

= Polonian, adj.2

(of a play or a part in a play) that is of sufficient quality or interest to be well-received regardless of the quality of the actor or performance.

Resembling or characteristic of Shakespeare's Ophelia, esp. in tending towards insanity or suicidal thoughts.