Shakespearian Actors

As in "classically trained Shakespearian actor". These actors (male and female), usually Brits, have had some serious training--often a stint at the Royal Shakespeare Company--and so have developed redoubtable acting skills.

Of course, they won't necessarily limit themselves to Shakespeare -- or even to theater. It's entirely possible for these people to do comedy, appear in major action movies and even enter Large Ham territory at times (see, for instance, Brian Blessed).

Used intelligently, Shakespearian Actors can raise everyone's game, or turn a blah character into a Breakout Character. But beware: being cast alongside one or more Shakespearian Actors makes it painfully clear if someone can't act (see, for instance, Teaching Mrs. Tingle, in which Helen Mirren out-acts all of her co-stars combined with her hands quite literally tied behind her back). Think of them as the acting equivalent of Spandex: they make good things better, and bad things much, much worse.

Because these actors will be critically acclaimed (they can be popular as well), they are more likely than most actors, if they're British, to succumb to the K-strain of Knight Fever, i.e. getting a knighthood.

One of the litmus tests for being a Shakespearian actor is to have played a major/lead role for the Royal Shakespeare Company. The RSC is probably the most prestigious theatre company in Britain, performing (almost) exclusively Shakespeare. (The closest North American equivalents are probably the Stratford Shakespeare Festival in Ontario and the Oregon Shakespeare Festival in Ashland.) Even better, see the YouTube entries for the old educational series, Playing Shakespeare, featuring the RSC players of its day, now in retrospect chock full of future movie stars like Patrick Stewart, Dame Judi Dench, Ben Kingsley, and Sir Ian McKellen.

Shakespearian Actors in fiction
As we've just seen, real-life Shakespearian Actors take a variety of roles for a variety of reasons, and few jobbing actors--even among this exceptionally talented bunch--can afford to be picky about the sorts of roles they accept. In fiction, though, the Shakespearian Actor tends to be a particular subtype of the high-maintenance diva archetype: one who constantly laments his decision to give up theater and who has nothing but contempt for the tripe he's being asked to deliver. This version is the Classically-Trained Extra.

Real examples:

 * Roger Allam: Old hand at the RSC, has turned his hand to film, musicals, television and radio.
 * Cate Blanchett: While not a member of the RSC, is a classically trained theatre actress with a Shakespeare background.
 * Brian Blessed
 * Hugh Bonneville, aka the Earl of Grantham.
 * Kenneth Branagh: Almost singlehandedly revived the Shakespeare film genre with a string of hits in the Nineties.
 * Jeremy Brett
 * Brian Cox.
 * Benedict Cumberbatch has not played for the RSC, but has acted in classic theater at venues including the National Theatre and the Royal Court Theatre; he has twice been nominated for an Olivier Award (winning for Frankenstein at the National in 2012) and has the same reputation for excellence as any RSC alum.
 * Timothy Dalton: the fourth cinematic James Bond, and his background can be seen in the way he played 007. He also appears in Flash Gordon, a Nazi spy in Disney's The Rocketeer, and as a medium-sized ham in Hot Fuzz. Is also the last Lord President of the Time Lords. Also Mr. Pricklepants.
 * Daniel Davis has reportedly been in all but six of Shakespeare's plays, presumably thanks to his ridiculously good English accent. (He's from Arkansas.) Also performed with both the Oregon Shakespeare Festival and the Stratford Shakespeare Festival.
 * Dame Judi Dench: M in the last half-dozen or so James Bond films. Also stole Shakespeare in Love as Queen Elizabeth I with roughly nine total minutes of screen time. She picked up an Academy Award as Best Supporting Actress for the performance.
 * Chiwetel Ejiofor, the Operative from Serenity. Has played Othello and Orsino from Twelfth Night.
 * Both Ralph Fiennes and Joseph Fiennes (the latter played the title role in Shakespeare in Love).
 * Kate Fleetwood
 * Sir John Gielgud
 * Sir Alec Guinness aka Obi-Wan Kenobi: Spoke the very first lines at the Stratford Festival (namely, "Now is the winter of our discontent").
 * Jeremy Irons
 * Sir Derek Jacobi: Has entered the Large Ham zone by playing The Master in Doctor Who on two occasions (although one is non-Canon).
 * James Earl Jones
 * Raul Julia
 * Ben Kingsley
 * Alex Kingston of ER and Doctor Who fame.
 * Dan Lauria, the father on The Wonder Years.
 * Adrian Lester of Hustle
 * John Lithgow.
 * Sir Ian McKellen
 * Dame Helen Mirren
 * Eve Myles
 * Jason Narvy, Skull from Mighty Morphin Power Rangers to Power Rangers in Space, has a doctorate in the craft.
 * Also Olivia Tennet (Dr. K) from Power Rangers RPM. Shortly after her stint on the show, she left for the Globe Theatre in London to participate in workshops with the Young Shakespeare Company as a prize for winning a national Shakespeare competition in New Zealand.
 * Sir Laurence Olivier, Lord Olivier: the Shakesperian actor.
 * Nathaniel Parker of The Inspector Lynley Mysteries fame
 * Christopher Plummer
 * Sir Ralph Richardson
 * Alan Rickman
 * Liev Schreiber is one of the more prominent Americans of this type.
 * William Shatner performed at the Stratford Festival in the 1960s. He repeated some of his roles on TV as well.
 * Sir Patrick Stewart: his classical training has allowed him to dodge being type cast by either Star Trek or X-Men, and he's returned to the RSC since (most recently, as Claudius to David Tennant's Hamlet).
 * Catherine Tate did small parts in her youth for the RSC, and is now playing Beatrice opposite David Tennant's Benedick in Much Ado About Nothing.
 * David Tennant, the Tenth Doctor in Doctor Who, was an RSC man (including a well-regarded Romeo) before his stint in the TARDIS, and moonlighted as a critically-acclaimed Hamlet between filming the 2009 specials. He's currently playing Benedick opposite Catherine Tate in Much Ado About Nothing.
 * In addition to Fiennes and Rickman, many Harry Potter actors:
 * Michael Gambon (the second Dumbledore)
 * Zoe Wanamaker (Madam Hooch)
 * Timothy Spall (Peter "Wormtail" Pettigrew)
 * Imelda Staunton (Dolores Umbridge)
 * Maggie Smith (Professor McGonagall)
 * Kate Fleetwood (Mary Cattermole)
 * Helen McCrory (Narcissa Malfoy)
 * Polly Walker (Atia of the Julii of Rome fame).
 * David Warner
 * Orson Welles