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Ken 10 is the ninth episode of the fourth season of Ben 10, and the forty-ninth episode overall.


In a possible future, Four Arms is fighting Vulkanus and transforms back into Ben 10,000 and places Vulkanus in a Null Void egg. Ben 10,000 then transforms into XLR8 and runs off to his headquarters. When he arrives, his son, Kenny, is celebrating his 10th birthday. Ben 10,000 gives Max Vulkanus's Null Void egg to place into the Null Void. Kenny explains to his party guests about what Ben does. Gwendolyn arrives in a hologram and gives Kenny a rock creature as a pet. Kenny blows out the candles on his cake and opens presents. Max gets him a hoverboard and he gets several other toys. Finally, Ben comes and gives Kenny his gift: which is an Omnitrix that comes pre-loaded with 10 aliens and a limiter, which Kenny doesn't like. An alarm rings and both Tennysons transform into XLR8. The XLR8s run off and fight Sploot. XLR8 (Ben 10,000) transforms into Cannonbolt while XLR8 (Ken) gets stuck in slime. Cannonbolt transforms into Heatblast, and then transforms back into Ben 10,000 before getting Sploot with a Null Void egg. Diamondhead fights Mot Snikrep as a boy watches on a screen. Diamondhead transforms into Spitter and Ken as Buzzshock attacks as well. Buzzshock is about to defeat Mot Snikrep, but Arctiguana freezes him before Buzzshock can win. At HQ, Ben 10,000 gives Max Snikrep's Null Void egg. Kenny is upset because Ben didn't let him do anything. Ben says that Ken's job is to watch and learn. Kenny storms off on his hoverboard. He rides with another boy, Devlin, and they compete to do tricks. Kenny transforms into Wildvine to win. Afterwards, the boys become friends. That night, an alarm goes off because someone is attacking HQ. The door blows up and it is Kevin 11.

Ben sends Kenny away, believing Kevin too dangerous to fight. Ben transforms into Four Arms, who walks off to fight. Four Arms and Kevin fight and Four Arms transforms into Cannonbolt. Kenny, in his room, notices a vent. Cannonbolt transforms into XLR8 in the Null Void chamber. XLR8 tells Kevin that he moved to projector and readies an egg. Grey Matter comes out of the vent, but he reverts back into Kenny. XLR8 is surprised to see him. Kevin leaves and Benmummy gets Kenny out of the vent. Kenny gets angry at Ben and storms off. The next day, Kenny and Devlin speak about their dads. Devlin suggests that he and Kenny find the Null Void projector and they fly off. They go to the Rust Bucket after Max gets out and walks away. They sneak in and look for the Projector, which Kenny believes is in the Rust Bucket. Kenny transforms into Ditto and creates clones to look for the Projector. Outside, Gwen tells Ben that he needs to give Kenny a chance to earn his trust. One of the Dittoes finds the room with the Projector and he, Devlin, and Kenny's pet go in. Devlin mutates into Kevin's original mutant form and releases his father just in time for Ben to arrive. Kevin runs up to and grabs Ditto, who reverts back into Ken, and he reveals that being imprisoned in the Null Void was the best thing that ever happened to him as he has now absorbed that powers of 11, 000 aliens and transforms into an even more monstrous form than before. Kevin mercilessly attacks Ben, Ken and even his own son Devlin, who asks that his father spares their lives. While Ben takes the fight outside, Ken has an idea to defeat Kevin.

Ben transforms into Four Arms and he still fights Kevin, but as before Kevin weakens Four Arms, who transforms back into Ben. Ken transforms into Grey Matter to enter and later transforms into Spitter and then transforms into Buzzshock. After Buzzshock transforms back into normal, Ken reveals he used Grey Matter's brain to hack & remove the Omnitrix's limiter; no limiter, no timing out Kevin grabs Ken and says that it still won't save him. Kevin is about to throw Ken, but Devlin comes in to defend him. Devlin explains why he freed Kevin - he wished his father would have cared about seeing his son again, but instead finds that he only cares about killing the Tennysons. Devlin cries upon this realization but then resumes fighting against his father. Ken transforms into XLR8. Devlin and XLR8 are thrown away and XLR8 transforms back into Ken who passes out.

Ben wakes up and sees what happened to Ken, angering him. Ben transforms into Way Big and mercilessly crushes Kevin, who transforms back to normal and Way Big transforms back into Ben, but Kevin is still capable of standing. Kevin is about to attack Ben and Ken again, but Devlin imprisons Kevin in a Null Void Grenade. Max states that he has a 'special place' reserved for Kevin so that he can't absorb any more alien DNA. Ken asks Ben if he can use all ten thousand of his heroes, but Ben says not to push his luck.

Devlin is about to leave until Ben nods to Max, who grabs the boy. When Devlin asks if they will throw him in the Null Void too, Ken opposses to this by standing in front of Devlin and Max and Ben say that they could do that or Devlin can stay with them and be part of their family, so Devlin becomes part of the Tennyson family. Later, Ken's rock pet regenerates and is alive again making him happy.

Noteworthy Events

Major Events

  • Ken receives his own Omnitrix and meets Devlin.
  • Kevin escapes from the Null Void.
  • Devlin moves in with the Tennysons.

Character Debuts



Aliens Used

By Ben 10,000

By Ken



Four Arms: (about Vulkanus) I do not have time for this. There's no way I'm missing another one of his birthdays, so I'd appreciate it if you just chill out in the Null Void! (reverts back to his human form and sends Vulkanus to the Null-Void)
Ben 10,000: Some scum just can't take a hint. (turns into XLR8)
(XLR8 runs to his HQ and reverts to his human form)
Ben 10,000: Told you I wouldn't miss your birthday.
(Ken sees him and hugs him)
Ken: Thanks, Dad.
Ben 10,000: You only turn 10 once.
Ken's Friends: Happy birthday, Kenny!

Quotes Right.png


Kevin: I guess I should thank you. With all that time in the Null Void, I was able to absorb a few tricks from all the aliens you locked in there with me. (transforms into his mutant form) Ben 10,000, meet Kevin 11,000!

Quotes Right.png


Kevin: (laughs manically, but is suddenly crushed by a tremendous fist; camera zooms out to reveal Way Big)
Way Big: How dare you! (with no mercy, he starts rapidly slamming his fists on Kevin)

Quotes Right.png

Naming and Translations

Language Name Origin
Croatian Ken 10 Ken 10
Hungarian Ken 10 Ken 10
Italian 10 Eroi per Ken 10 Heroes for Ken
Polish Ken 10 Ken 10
Portuguese (Br) Ken 10 Ken 10
Romanian Ken 10 Ken 10
Russian Приключения Кена Ken's Adventures
Spanish (HA) Ken 10 Ken 10
Spanish (Spain) Ken Ten Ken Ten


Voice Actor Role(s)
Tara Strong Ken Tennyson
Gwendolyn Tennyson
Paul Eiding Max Tennyson
Jim Ward XLR8
Richard McGonagle Four Arms
Fred Tatasciore Ben 10,000
Way Big
Richard Horvitz Grey Matter
Charlie Schlatter Devlin Levin
Kevin 11,000
Rob Paulsen Ditto


  • This episode takes place in the same future seen Ben 10,000, albeit 12 years later.[pop-up 1]
  • Ben 10,000 moved the Null Void Chamber from its original location after Dr. Animo broke in, which occurred in Ben 10,000.
  • Devlin is approached by Ben and Max with the same offer they gave Kevin when they were younger, as seen in Kevin 11.[pop-up 2]



  • All the children who attend Ken's birthday party previously made cameos in Ben 10,000 and seem to have not aged since then, due to their models being reused.
  • The party is for Ken's 10th birthday, yet his cake is erroneously depicted with 11 candles.
  • When Four Arms throws Devlin, his back is drawn incorrectly.
  • When Kevin 11,000 is seen on top of the Null Void containment unit, he has white lines on his shoes.
  • When Kevin 11,000 is in his mutant form, sometimes his toes are red, other times they are grey.
  • When Four Arms punches Kevin 11,000, he has five tentacles.
  • Even though Ken was able to unlock the Master Control, his Omnitrix times out after he is knocked out by Kevin 11,000.
  • Before Way Big slams his fist on Kevin 11,000, he has seven tentacles.



Kersti Myrberg

Tom Perkins

Dwayne McDuffie

Derrick J. Wyatt


Ben 10 Episodes