|— Stoick names the Rumblehorn|
As shown in "Crushing It", Skullcrusher was the first Rumblehorn found by Berk's Dragon Riders on Dragon's Edge. They believed that he was trying to destroy the Edge and drive them out, when in reality he was attempting to warn the riders of an incoming tidal wave. They spent some time trying to catch and relocate him until Stoick came to help and realized that he wasn't interested in destruction. Together with Stoick and the Riders, they were able to save the outpost from being wiped out, with the Rumblehorn proving particularly useful in completing the stone wall that had once been erected to keep him out. Stoick then named him Skullcrusher- on account of their mutual hard heads- and took him to Berk with him. He was also given Thornado's saddle, which was later upgraded by Stoick.
In "Team Astrid", as Stoick's dragon, he defended Berk when Dagur attacked. Skullcrusher then went with Stoick, Astrid, and Stormfly to aid Hiccup in defending Dragon's Edge. He and Stoick charged through a Berserker ship and sunk it, but got caught in one of the ship's nets in doing so. However, Stoick was able to free him and he then fought alongside the Dragon Riders' Auxiliary, driving Dagur away.
During the events of "Turn and Burn", Skullcrusher then assisted Stoick in tracking down Spitelout when he went missing for a month. Together, along with Hiccup, Snotlout and their dragons, they found him and Kingstail on Storehouse Island. However, they came under attack by the Singetail. They were unable to drive it away and were forced to give up the island when other Singetails arrived. Before leaving, Skullcrusher and Stoick took the "S" from the storehouse.
When Hiccup talks to Stoick about how Viggo will come after Berk's dragons in "Last Auction Heroes", Stoick looks at a sleeping Skullcrusher and agrees with Hiccup's plan. Skullcrusher is then seen playing with Toothless at the Academy.
In "Shell Shocked, Part 1", Stoick and Skullcrusher take part in Hiccup's mission to retrieve the Dragon Eye from Viggo. However, when they arrive at the Hunters' base, they find it devastated. Skullcrusher then returns to Berk with Stoick.
When Krogan's forces temporarily overtook Dragon's Edge in "The Wings of War, Part 2", Stoick and Skullcrusher led an attempt to reclaim it. The Rumblehorn and his rider fought an arduous battle against the Flyers, though the tide turned in their favor when Hiccup, Spitelout and Gustav enact a plan to have the Singetails abandon their Flyers. Later on, Skullcrusher and Stoick accompanied Astrid and Stormfly in chasing down Krogan and Viggo, avoiding the barrage of fireballs created by Krogan's Singetail before being hit and thrown off course. Skullcrusher and Stoick manage to recover before making a safe landing.
Stoick was outraged when he learned about Johann's true allegiance in "No Bark, All Bite", and Skullcrusher did not hesitate when the Hooligan chief commanded him to burn all of Johann's latest shipments. He later accompanied Stoick, Hiccup and Toothless in their search for willow bark, fighting off Dragon Flyers along the way. When Hiccup and Stoick's relationship became strained through their arguments, Skullcrusher and Toothless work together in having their riders forgive one another. The group soon fly back to Berk when they realize Johann's true plan, and Skullcrusher helped Stoick in confronting Krogan to give Hiccup and Toothless time to free the imprisoned dragons and retake Berk from the Hunters and Flyers.
In "Darkest Night", Stoick and Skullcrusher were out patrolling on their own when they got ambushed by Dragon Flyers. Skullcrusher successfully sent an S.O.S. to the other Dragon Riders before being incapacitated by the Singetails' fireballs. Despite his condition, Skullcrusher managed to rescue his rider from certain death and was carried back to Berk by Grump to make a complete recovery.
Stoick and Skullcrusher are shown to be close, with Stoick being comfortable riding Skullcrusher alongside Grump and Gobber.
When Hiccup went with Toothless to try and reason with Drago Bludvist, Skullcrusher helped Stoick, Gobber and Grump to track down Hiccup. They were then able to find Hiccup and encountered Stoick's wife, Valka at her mountain. He, along with Stoick, Hiccup, Gobber, Valka, and their dragons then defended the mountains against Drago's Army.
Following Stoick's death, Hiccup suggests that Skullcrusher passes into the care of their new ally and former dragon trapper Eret, Son of Eret, recognizing Eret's skill and courage in helping Berk defeat Drago Bludvist. After Drago's defeat, he and Eret then took part in Berk's Dragon Races.
On the island, unlike the other dragons, Skullcrusher isn't attracted to the hot pools, but he still doesn't find anything out of the ordinary.
At dinner, after Calder reveals his true nature, Skullcrusher prepares ready to fight. However, due to being outnumbered, the riders surrender.
After Hiccup escapes, he brings the dragons, including Skullcrusher, and they all prepare to leave the island. However, right then, some Foreverwings wake up and began destroying the village. Although he does not appear while the riders help the people of Nepenthe, after Hiccup defeats Calder, he carries Eret to the scene, to see what happened. He then returns to Berk.
Skullcrusher looks like a cross between a Triceratops and a scarab beetle (due to his neck plates).
In comparison to Grump, Skullcrusher is stern and serious looking, and sometimes a little stubborn, (corresponding with the personality of Stoick). He always has his nose to the ground, following a scent, as is typical for his species.
He can be friendly, especially towards his rider. He is doggedly determined once he has caught a scent. He is caring and a natural leader, warning the other dragons of an oncoming tsunami to ensure their safety.
Skullcrusher also has a playful side, like spinning around while flying. He was also seen playing a bit with Toothless in "Last Auction Heroes".
- Tracking: Like all Rumblehorns, Skullcrusher has a keen sense of smell, enabling him to track anything once he has caught the scent.
- Strength: Skullcrusher is extremely strong and quite capable of destroying any dragon traps he encounters using his tail and jaws. Skullcrusher can charge with his head lowered and horns displayed to do some serious damages. He also doesn't have trouble carrying large Vikings on his back such as Stoick and extra weight of Hiccup. Skullcrusher's extreme strength was greatly proven when he was able to ram down a sea stack when flying at full speed towards it, as well as during the time when he charged clear through a Berserker ship and sunk it into the ocean.
- Endurance: Skullcrusher is able to recover rather quickly after being directly hit by a Singetail's fireball.
- Fire: Skullcrusher can shoot burning, explosive missiles from his mouth that can do a lot of damage.
- Acrobatics: Skullcrusher has some impressive agility in the air despite of his large size.
- Speed: Skullcrusher is also surprisingly quick on his feet and in the air.
- Intelligence: Skullcrusher has shown to be able to try to figure out ways to make other dragons to flee the island before they could be killed.
|Films and Shorts|
|"How to Train Your Dragon":||Absent||"Legend of the Boneknapper Dragon":||Absent|
|"How to Train Your Dragon 2":||Appears||"Gift of the Night Fury":||Absent|
|"How to Train Your Dragon: The Hidden World":||Absent||"Book of Dragons (Short)":||Absent|
|"Dawn of the Dragon Racers":||Absent|
|Race to the Edge, Season 1|
|1. "Dragon Eye of the Beholder, Part 1":||Absent||8. "Crushing It":||Appears|
|2. "Dragon Eye of the Beholder, Part 2":||Absent||9. "Quake, Rattle and Roll":||Absent|
|3. "Imperfect Harmony":||Absent||10. "Have Dragon Will Travel, Part 1":||Absent|
|4. "When Darkness Falls":||Absent||11. "Have Dragon Will Travel, Part 2":||Absent|
|5. "Big Man on Berk":||Absent||12. "The Next Big Sting":||Absent|
|6. "Gone Gustav Gone":||Absent||13. "Total Nightmare":||Absent|
|7. "Reign of Fireworms":||Absent|
|Race to the Edge, Season 2|
|1. "Team Astrid":||Appears||8. "Edge of Disaster, Part 1":||Absent|
|2. "Night of the Hunters, Part 1":||Absent||9. "Edge of Disaster, Part 2":||Absent|
|3. "Night of the Hunters, Part 2":||Absent||10. "Shock and Awe":||Absent|
|4. "Bad Moon Rising":||Absent||11. "A Time to Skrill":||Appears|
|5. "Snotlout Gets the Axe":||Absent||12. "Maces and Talons, Part 1":||Absent|
|6. "The Zippleback Experience":||Absent||13. "Maces and Talons, Part 2":||Absent|
|7. "Snow Way Out":||Absent|
|Race to the Edge, Season 3|
|1. "Enemy of My Enemy":||Absent||8. "Stryke Out":||Absent|
|2. "Crash Course":||Absent||9. "Tone Death":||Absent|
|3. "Follow the Leader":||Absent||10. "Between a Rock and a Hard Place":||Absent|
|4. "Turn and Burn":||Appears||11. "Family on the Edge":||Absent|
|5. "Buffalord Soldier":||Absent||12. "Last Auction Heroes":||Appears|
|6. "A Grim Retreat":||Appears||13. "Defenders of the Wing, Part 1":||Absent|
|7. "To Heather or Not to Heather":||Absent|
|Race to the Edge, Season 4|
|1. "Defenders of the Wing, Part 2":||Absent||8. "Gold Rush":||Absent|
|2. "Gruff Around the Edges":||Absent||9. "Out of the Frying Pan":||Absent|
|3. "Midnight Scrum":||Absent||10. "Twintuition":||Absent|
|4. "Not Lout":||Absent||11. "Blindsided":||Absent|
|5. "Saving Shattermaster":||Absent||12. "Shell Shocked, Part 1":||Appears|
|6. "Dire Straits":||Absent||13. "Shell Shocked, Part 2":||Absent|
|7. "The Longest Day":||Absent|
|Race to the Edge, Season 5|
|1. "Living on the Edge":||Absent||8. "The Wings of War, Part 1":||Absent|
|2. "Sandbusted":||Absent||9. "The Wings of War, Part 2":||Appears|
|3. "Something Rotten on Berserker Island":||Absent||10. "No Dragon Left Behind":||Absent|
|4. "Snotlout's Angels":||Absent||11. "Snuffnut:||Absent|
|5. "A Matter of Perspective":||Absent||12. "Searching for Oswald... and Chicken":||Absent|
|6. "Return of Thor Bonecrusher":||Absent||13. "Sins of the Past":||Absent|
|7. "Dawn of Destruction":||Absent|
|Race to the Edge, Season 6|
|1. "In Plain Sight":||Absent||8. "Triple Cross":||Absent|
|2. "No Bark, All Bite":||Appears||9. "Family Matters":||Absent|
|3. "Chain of Command":||Absent||10. "Darkest Night":||Appears|
|4. "Loyal Order of Ingerman":||Absent||11. "Guardians of Vanaheim":||Absent|
|5. "A Gruff Separation":||Absent||12. "King of Dragons, Part 1":||Absent|
|6. "Mi Amore Wing":||Absent||13. "King of Dragons, Part 2":||Absent|
|7. "Ruff Transition":||Absent|
|"The Serpent's Heir":||Appears||"The Fire Tides":||Absent|
|"Dragons: Rise of Berk":||Appears||"School of Dragons":||Mentioned|
|"How to Train Your Dragon":||Absent||"How to Train Your Dragon 2":||Absent|
|"DreamWorks Dragons: Wild Skies":||Absent|
- An image error in Empire Magazine led to believe that the Thornridge was a new dragon species with the same name. The description and combination of animals were indeed about the Rumblehorn.
- Along with Thornado, he is the first Dragon whose current/former rider is deceased.
- He is the first Dragon who had more than one rider, excluding Barf and Belch.