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Sonic Wiki Zone
Sonic Wiki Zone

I'd like you to meet your older brother, E-101. Just call him Beta.

Dr. Eggman, Sonic Adventure

E-101 (E-101 Ī 101?), codenamed β or Beta (ベータ Bēta?), is a character that appears in the Sonic the Hedgehog series. He was the first E-100 Series robot created by Dr. Eggman during the Chaos incident to aid in the destruction of Station Square.[1] Initially intended to serve onboard the Egg Carrier, Beta lost the position to his "younger brother" E-102 Gamma. As such, he was discarded by Dr. Eggman and upgraded into E-101 Beta Mk. II.


E-101 Beta was a humanoid robot colored in black and white. He possessed no neck, his head and torso coming together in an almost ellipsoid shape. His torso was black with a wide and white vertical stripe down the middle and possessed a head light with a hexagonal gray frame on the right side. He also had gray mufflers surrounding the pelvis area and had the number "101" painted in white on the right of his large vertical stripe and the left side of his rear. His head meanwhile was small and platform-like with a yellow shade and green cylindrical eyes. He also had a Jet Booster hovering behind his neck.

Beta's shoulders were black vertical cylinders. Attached to each of them were Beta's arms, which were long and designed with two joints; each of Beta's forearms were designed as black gun barrels. Also, Beta's upper arms were black, while the parts between his upper arms and forearms were gray. Beta also possessed two long and inverted legs with five points of articulation and large, black feet with two sharp toes and roller wheels on the heels. The upper sections of his legs in particular were black while the rest of them were gray, except from his calves, which were thick and black.


Sonic Adventure[]

In Sonic Adventure, its enhanced port Sonic Adventure DX: Director's Cut, and the 2010 remaster, Beta was created as the first unit in the E-100 Series of shooting robots in order to aid Dr. Eggman in his agenda to destroy Station Square and build Eggmanland on its ruins.[1] While Beta went to the Final Egg shooting range to practice, Dr. Eggman finished constructing Beta's younger brother E-102 Gamma.

Shortly after Gamma's test-run, Beta was summoned by Dr. Eggman and was pitted against Gamma to decide which of them would get a position among the crew onboard Dr. Eggman's Egg Carrier. Despite having the odds in his favor, Beta was defeated by Gamma. Not beaten in spirit however, Beta mutely appealed to his creator to still come along. Interested, Dr. Eggman eventually allowed Beta the privilege on the grounds that they could "always use a spare set of parts".


Beta being rebuilt into E-101 Beta Mk. II, from Sonic Adventure.

Having been regarded obsolete, Beta was relegated to an Egg Carrier robotics lab. There, Beta underwent a torturous remodeling operation into the more powerful E-101 Beta Mk. II where he was physically dismembered, and his old limbs were discarded on the floor while mechanical arms worked on him. In the midst of this process, Gamma stumbled into the lab and saw the operations on Beta. This horrible sight served as the breaking point for Gamma that set him on the road to apostasy, eventually making him betray Dr. Eggman and delete him from his master registration.

E-102 SA Fin

The bird inside E-101 Beta (left) is reunited with the bird inside E-102 Gamma (right), from Sonic Adventure.

Eventually, E-101 Mark II was finished and escaped from the Egg Carrier, but was soon confronted by Gamma, as a part of the former's crusade to "free" his brothers from Dr. Eggman's control. E-101 Mark II was destroyed, but not before fatally wounding Gamma as well. This still succeeded in carrying out Gamma's goal and allowed the birds inside the two robots to fly away together.

Sonic Heroes[]

In Sonic Heroes, both Beta and Gamma are mentioned by Omega when Team Dark gets an E-Rank in a stage, in which the robot believes himself to be inferior to the two earlier models.

Sonic Rivals[]

Card 133 (Sonic Rivals)

The E-101 Beta collectable card, from Sonic Rivals.

In Sonic Rivals, Beta appears as a collectable card.


A silent robot, Beta behaved overall emotionless, but possessed a degree of free will and autonomy. Beta was best defined by his loyalty to Dr. Eggman, whom it only sought to please, as per its directive. As such, it followed Dr. Eggman's orders without question. Most noticeably, Beta showed somewhat of a determined spirit; after being defeated by E-102 Gamma and losing his place onboard the Egg Carrier, Beta chose to plead for a chance to come along with Dr. Eggman anyway.

Powers and abilities[]

As a part of the E-Series, Beta was a very advanced robot that was developed to advance weaponry.[2] According to Dr. Eggman, Beta was even more advanced and powerful than E-102 Gamma was.[3]

Beta was re-equipped with small twin cannons fitted to each arm that could fire powerful missiles. He also possessed a Jet Booster that enabled him to slowly hover through the air for a safe landing. Additionally, as shown by his design, Beta could change his body frame when crouching down which let him roll on a set of wheels behind his feet to increase his speed.





It's brother versus brother in a cruel duel for survival.

— Description, Sonic the Hedgehog Encyclo-speed-ia

E-101 Beta is the first boss in E-102 Gamma's storyline in Sonic Adventure, its enhanced port Sonic Adventure DX: Director's Cut, and the 2010 remaster. In Adventure Mode, he is fought at the Final Egg in the Mystic Ruins Jungle Area after finishing its Action Stage. In Trial Mode, the player can battle him as the first boss in the Boss Sub Game. Beta is only encountered with Gamma.

Boss guide[]

E-101 Beta is a simple, albeit moderately tough foe, but Gamma can target him, and fire faster than he can. During the fight, Beta will stand in one spot and shoot homing missiles at Gamma or fly into midair with his Jet Booster. The player must target his missiles and the robot himself with the Laser Gun and then fire the Homing Missile Launch, while staying at a distance in order to evade attacks. After landing three blows on Beta, this boss will be defeated.


Title Artist(s) Music Length
"Heartless Colleague ...Boss: E-Series Targets " Jun Senoue, Yoshitada Miya 1:25



Sonic Adventure DX - Gamma Boss 1 - E101 Beta (no damage) 1080p

In other media[]


Sonic X[]

Main article: E-101 Beta (Sonic X)
E-101 Beta Sonic X

E-101 Beta in Sonic X.

In the Sonic X anime series, Beta was one of Dr. Eggman's E-100 Series robots, created during the Chaos incident. Shortly after being brought online, Beta was sent out to capture Froggy. After failing its mission, Beta was relegated to a robotics lab onboard the Egg Carrier where it was rebuilt into E-101 "Kai". Shortly thereafter, Beta fought E-102 Gamma. Their fight ultimately ended in a draw, with both robots taking each other out.

Books and comics[]

Archie Comics[]

Main article: E-101 Beta (Archie)

In the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics, E-101 Beta was destroyed by E-102 Gamma, similar to what happened in Sonic Adventure.


  • Beta is the only E-Series robot to lack yellow cuffs on his limbs, featuring uniform silver cuffs throughout his entire design. Despite this, his head remained yellow in color up until his Mark II upgrade, where it became uniform silver with the rest of his colors.
  • Although he does not have a functional forearm due to his missile upgrade, a mirror reflection of what would have been Beta's original forearm appears on his front skirt plate. This is due to the fact the reflection is an actual painted image within Beta's texture, which was repurposed from Gamma's textures.
  • Strangely, any time Beta is seen in the ending shots found in the credits of Gamma's story mode in the Dreamcast version of Sonic Adventure, he does not feature his jet booster or twin arm cannons, appearing as a black version of Gamma disregarding his specific numbering and lack of targeting sight. Similarly, when found in the middle of his reconstruction, Gamma looks down and sees Beta's discarded parts on the ground, oddly including his standard arm blaster rather than his twin arm cannons.




  1. 1.0 1.1 "All Star Cast". Sonic Adventure Tokyo International Forum Unveiling Booklet. 22 August 1998. p. 9.
  2. Toyoda, Eitaro (2017). "Dr. Eggman in... My Greatest Invention". Sonic the Hedgehog: Rival Edition. Tomy.
  3. Sonic Team (27 June 2003)). Sonic Adventure DX: Director's Cut. Nintendo GameCube. Sega. Area/level: Mystic Ruins Jungle Area. "Dr. Eggman: Enter, Gamma! You are not as advanced as Beta is, but you'll do fine."

Main article · Scripts (Sonic, Tails, Knuckles, Amy, Big, Gamma, Super Sonic) · Story Screens (Sonic, Tails, Knuckles, Amy, Big, Gamma) · Credits · Glitches · Beta elements · Gallery · Pre-releases (Limited Edition, DX Demo Version) · Re-releases (DX, 2010)