E-101 Beta (E-101 "ベータ" E - 101 "Bēta"?), or E-101 “β”, is a character that appears in Sonic Adventure and Sonic Adventure DX: Director's Cut. He was the first animal-powered E-100 Series robot created by Dr. Eggman. 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 Eggman and upgraded into E-101 Mark II.


E-101 Beta was created by Dr. Eggman as the first of the doctor's E-100 Series robots, with a grey-feathered Flicky bird serving as his power source. While Beta went to the Final Egg shooting range to practice, Eggman finished constructing Beta's younger brother E-102 Gamma.

Shortly after Gamma's test-run, Beta was summoned by 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, 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 Mark II.

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 Mark 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.

Eventually, E-101 Mark II was finished and escaped from the Egg Carrier, but was quickly confronted by Gamma, as a part of the former's fratricidal crusade to "rescue" his brothers from Eggman's control by destroying them. E-101 Mark II was destroyed, but not before fatally wounding Gamma as well.

Powers and abilities

Being a model in Dr. Eggman's E-100 series, Beta was built for combat. According to Dr. Eggman, Beta was even more advanced and powerful than E-102 Gamma was.[1][2]

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.


Boss guide

E-101 Beta is a moderately tough foe, but Gamma can target it and fire faster than it can. The player must target his missiles and the robot himself, while staying at a distance in order to evade attacks.


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

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 appears in Sonic X. During the Chaos Saga of the show, Beta mirrored several key points in its original story line and also gained more scenes by taking most of E-105 Zeta's role from the game.

One of these key features that was not present in Sonic Adventure is Beta's ability to speak. Like ZERO in Sonic Adventure, he was also unable, or at least not shown, to speak and could only respond by "Body Language" - in his case, interrupting Eggman and giving signals via movement and its blank facial expression. Beta also goes out to find Froggy along with the other E-Series robots, something which Zeta had originally done; in the game, Beta was already undergoing its modification process.

Like the other E-Series robots in Sonic X, Beta's new voice was very high-pitched and, according to fans, unenthusiastic, as opposed to in Sonic Adventure where the robots spoke in a manner that, while still being slightly robotic, was very intelligent and much more human than drone-like.

Archie Comics

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 and Gamma are mentioned in Sonic Heroes; when Team Dark gets an E Rank, if E-123 Omega gets the highest score of the three teammates he will say "I couldn't even beat Gamma or Beta.".
  • 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.
  • It is assumed that Beta's discarded Missile Launcher arms were used on Delta, as Delta became identical to Beta's original configuration after being jettisoned from the Egg Carrier.
  • Beta is one of two E-Series robots in Sonic Adventure to receive a physical Level-Up Item (the other being Zeta). The remaining E-Series, including Gamma, only received enhanced Arm Cannons (and a Jet Booster).
  • 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, he does not feature his jet booster or twin arm cannons, appearing as a black version of E-102 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. Sonic Team, Sonic Team USA (June 27, 2003). Sonic Adventure. GameCube. Sega. Level/area: Egg Carrier Adventure Field. "Eggman: "Enter, Gamma! You are not as advanced as Beta is, but you'll do fine"
  2. Sonic Team, Sonic Team USA (June 27, 2003). Sonic Adventure. GameCube. Sega. Level/area: Egg Carrier Adventure Field. "Eggman: "I am pitting the two of you against each other, and the winner serves on my ship. I put my bets on Beta, but I owe you at least a fair chance."

Main article | Gallery | Beta Elements | Staff | Glitches | Re-releases (DX | 2010)
Scripts (Sonic, Tails, Knuckles, Amy, Big, Gamma, Super Sonic)