19 challenging 'Game of Thrones' trivia questions that even die-hard fans might have trouble with

The first book in Martin's "A Song of Ice and Fire" series, "A Game of Thrones," was published in 1996.

The first-ever episode of "Game of Thrones" aired April 17, 2011.

(Bonus fact: April 17 just happens to be actor Sean Bean's birthday.)

R + L = J stands for Rhaegar Targaryen + Lyanna Stark = Jon Snow.

The theory, which correctly guessed Jon Snow's real parentage, is one of the oldest fan predictions.

Each of the five Stark children, plus Jon Snow, adopted a direwolf pup in the very first episode of "Game of Thrones." The wolves were named Ghost, Grey Wind, Lady, Summer, Nymeria, and Shaggy Dog.

In the original cut of the episode, a prosthetic mold of President George W. Bush could be seen in the background when Joffrey forced Sansa to look at Ned Stark's head among the spiked traitors.

HBO and the series' showrunners issued statements of apology after this detail was picked up online. They explained that the Bush lookalike had been part of a bulk rented set of prosthetic body parts, and HBO called it an "inadvertent, careless mistake."

"We are sorry this happened and will have it removed from any future DVD production," HBO's statement read. Now Bush's likeness cannot be seen in streaming versions of the episode, nor on any hard-copy releases.

Catelyn Stark was born to House Tully in the Riverlands.

In Martin's novels, Theon Greyjoy's sister is named Asha.

Her name was changed for the show due to concerns that audiences would confuse Asha with Osha — the name of the wildling woman who helps Bran Stark escape from Winterfell.

Season three, episode nine was titled "The Rains of Castamere" (the name of the House Lannister-associated song that plays ominously before the massacre starts).

The Meereenese man quoted lines from "Monty Python and the Holy Grail" (translated into Low Valyrian) when he was mocking Daenerys.

David Peterson, the linguist who created the Valyrian languages for "Game of Thrones," said in an HBO interview that the "Monty Python" reference was showrunner D.B. Weiss' idea.

There were seven total musical-related cameos in all eight seasons of "Game of Thrones." You can read more about each appearance here, but every singer and band possible for the answer is listed below:

• Ed Sheeran
• Chris Stapleton
• Mastodon (Brann Dailor, Bill Kelliher, and Brent Hinds)
• Coldplay (drummer Will Champion)
• Snow Patrol (singer Gary Lightbody)
• Sigur Ros (Jónsi, Georg Hólm, and Ágúst Ævar Gunnarsson)
• Of Monsters and Men (Nanna Bryndís Hilmarsdóttir, Ragnar Þórhallsson, Brynjar Leifsson, Kristján Páll Kristjánsson, and Arnar Rósenkranz Hilmarsson)

1. Drogon (named for Khal Drogo)
2. Rhaegal (named for Rhaegar Targaryen)
3. Viserion (named for Viserys Targaryen)

The five kings referenced in the War of the Five Kings were Joffrey Baratheon (aka really Lannister), Renly Baratheon, Stannis Baratheon, Robb Stark, and Balon Greyjoy.

The "Cleganebowl" fan theory predicted that brothers Ser Gregor and Sandor Clegane would fight to the death.

The term first appeared in 2013 and was inspired by the 2013 Super Bowl, in which the coaches of the opposing teams also happened to be brothers Jim and John Harbaugh. Football fans and sports announcers nicknamed the game "The Harbowl."

Valar morghulis (which translates to "all men must die") is traditionally met with the phrase valar dohaeris ("all men must serve").

Piano sounds were used in the "Game of Thrones" score for the very first time in the season six finale, "The Winds of Winter."

The track, titled "The Light of the Seven," played over the long opening sequence where Cersei blows up the Sept of Baelor.

The House Lannister words are "Hear Me Roar."

People might mistake the saying associated with Lannisters (that they "always pay their debts") with their actual house words.

In the show, the three most prominent people Melisandre burned alive were Axell Florent, Mance Rayder, and Shireen Baratheon.

There are 73 total episodes of "Game of Thrones."

It was wedding music. Composer Ramin Djawadi used the same melody from Robb Stark and Talisa's wedding scene in season two for this shared moment between Brienne and Jaime.

Fans first noticed this connection, and then Djawadi confirmed the wedding theme in an interview with Insider.

"It's just a hint of what their relationship — if they had stayed together, if he was still alive — what it could have been," Djawadi said.

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• Why 'Game of Thrones' may not have 'spoiled' the ending of George R.R. Martin's books as much as you think