Witty, fierce, irreverent, intense: Janet McTeer’s performance as Sarah Bernhardt in Bernhardt/Hamlet is a storm of originality and intelligence—and it’s a lot of boisterous fun, too­­­.

Theresa Rebeck’s play, directed with by Moritz von Stuelpnagel for the Roundabout Theatre Company, evokes the moment in the late 1890s when Bernhardt, then 55,...