Who Died on Game of Thrones Last Night—and Who Killed Them?

Only two episodes in to season four, and Game of Thrones is already killing off major characters. As I did for episode one, I've put together a collection of scenes, references, and characters from episode two that deserve a special comment or mention—in particular, an investigation into season four's first major death.

Let's C.S.I. Westeros this. Finally, someone on this goddamn show whom we wanted to die actually did: little blond sociopath King Joffrey, poisoned at his wedding. But:

Who killed Joffrey?

Here's a list of all the people who had visible access to Joffrey's food or drink before he was poisoned, and/or had a motive to kill him:

Sansa

Who Died on Game of Thrones Last Night—and Who Killed Them?

Did she have access? Yes. Sansa picks up Joffrey's goblet when he kicks it under the table while attempting to humiliate Tyrion; she could easily have rubbed poison in it
Motive: Hates Joffrey; used to be engaged to him.

Tyrion

Who Died on Game of Thrones Last Night—and Who Killed Them?

Did he have access? Yes. Tyrion pours Joffrey's wine after Joffrey forces him to be cupbearer.
Motive: Hates Joffrey; is related to him.

Margaery

Who Died on Game of Thrones Last Night—and Who Killed Them?

Did she have access? Yes. Margaery feeds Joffrey his pie right before he chokes out and dies.
Motive: Hates Joffrey; has to marry him.

Dontos

Who Died on Game of Thrones Last Night—and Who Killed Them?

Did he have access? Unclear. But it's sketchy as hell at this dude shows up to drag Sansa away right when Joffrey dies.
Motive: Hates Joffrey; is Joffrey's fool.

Lady Olenna

Who Died on Game of Thrones Last Night—and Who Killed Them?

Did she have access? Yes, probably: Lady Olenna sits next to Margaery; Joffrey's wine is placed directly in front of her.
Motive: Hates Joffrey; is marrying her granddaughter to him.

Oberyn Martell

Who Died on Game of Thrones Last Night—and Who Killed Them?

Did he have access? Unclear. But, come on. This guy!
Motive: Hates Joffrey; also hates his dad.

Read on for more background, explanation, and annotation. What'd I miss? Add your own annotations, observations and comments by clicking "reply."