Sonic News Network

Know something we don't about Sonic? Don't hesitate in signing up today! It's fast, free, and easy, and you will get a wealth of new abilities, and it also hides your IP address from public view. We are in need of content, and everyone has something to contribute!

If you have an account, please log in.


Sonic News Network
Sonic News Network
For E-101 Mark II's original form, see E-101 Beta.

E-101 Mark II[5] (E-101改 Ī Ichi-Zero-Ichi Kai?, lit. "E-101 Revised"), also written as E101mkII, is a character that appears in the Sonic the Hedgehog series. It was an animal-powered robot and the upgraded form of E-101 Beta, an unit from Dr. Eggman's E-100 Series.

When E-101 Beta was allowed to stay on the Egg Carrier despite his failures, Dr. Eggman remade him into E-101 Mark II. When E-101 Mark II finally broke free though, he was destroyed by E-102 Gamma.


E-101 Mark II bears a strong resemblance to its previous form in terms of body shape and color scheme, but has been heavily modified into an airborne fighting machine. It has a round black torso with a large white vertical stripe, a large muffler surrounding the pelvic area, and "101" printed in white on its left side. It also has a black platform-like head with a large grey shade and a single green "eye" on its otherwise-featureless face that moves from side-to-side.

With its legs removed, E-101 Mark II's lower torso has been replaced with a rudder-like black and white tail, and two thin grey and green-colored thrusters on its lower torso, granting it impressive aerial maneuverability. Its arms are also equipped with large shield-like gauntlets with spikes that resemble those of the Shovel Claw. It also has powerful twin energy cannon weapons mounted underneath each gauntlet, replacing the old twin missile launchers its original counterpart had.


Sonic Adventure

When E-101 Beta lost in combat to his "younger brother" E-102 Gamma for position among the crew onboard Egg Carrier, it mutely appealed to its creator Dr. Eggman to come along. Eventually, Eggman was convinced on the grounds that they could "always use a spare set of parts."

Beta being rebuilt into E-101 Mark II.

Regarded obsolete, Beta was relegated to an Egg Carrier robotics lab where Eggman remodeled it into E-101 Mark II. There, Beta was physically dismembered, its old limbs being discarded on the floor while mechanical arms remade it. During this process, Gamma accidently stumbled into the lab with E-101 Mark II. This horrifying display of Eggman's callous cruelty even towards his own creations would serve as the breaking point that set Gamma on the road to apostasy and defection from the doctor.

E-101 Mark II lands the finishing blow on his brother.

After the Egg Carrier crashed, E-101 Mark II was completed and eventually escaped the air fortress's remains. Shortly after, E-101 Mark II faced off against Gamma, as a part of the former's fratricidal crusade to "rescue" his brothers from Eggman's control by destroying them. Despite its numerous improvements, E-101 Mark II was defeated by Gamma and seemingly felt motionlessly to the floor. However, with the last of its power, it shot Gamma at point-blank range, causing fatal damage to its younger brother and exerting its own power supply at last, finally destroying it in a large explosion.


E-101 Mark II's final act before its destruction, which was to destroy E-102 Gamma, ironically assisted in completing Gamma's mission by freeing the birds trapped within both of them. The bird released from E-101 Mark II would then be reunited with its other family members: a pink bird who had been powering Gamma and a blue bird who had been protected by Amy Rose, all three of them having been separated due to Eggman's evil ambitions.


E-101 Mark II is utterly silent and shows no signs of sentience. By comparison, E-101 Mark II showed even less individuality than its un-upgraded form, E-101 Beta, who displayed a desire to follow Eggman despite failing him. Regardless, it is fiercely dedicated to disposing its enemies, making it quite ruthless, as shown when it chose to attack Gamma on the brink of its defeat, an effort that resulted in its own destruction.

Powers and abilities

Following its upgrade, E-101 Mark II became a powerhouse of a fighting machine in almost every way over its previous form and was the strongest E-Series robot of its time.[2][6]

E-101 Mark II possessed jets and a tail-like rudder that granted it flight and super speed, enough to leave afterimages in its wake. It was also much more swift and agile than its previous form, being able to dodge missiles at extreme speed. Some of its new armaments included the ability to launch several guided missiles. It also had an advanced tracking system in its single green eye. Additionally, it was equipped with energy cannons that could fire yellow beams powerful enough to cause massive explosions upon impact and be charged for even greater power.

Besides weapon capabilities, E-101 Mark II could create rainbow-colored force-fields that could deflect projectiles and even be used offensively by ramming it into opponents. It was also capable of teleportation for avoiding attacks. Additionally, it had large and durable spiky shield-like gauntlets which could knock away missiles by backhanding them and be used for high-speed charging attacks.


E-101 Mark II is the fifth and final boss of E-102 Gamma's storyline in Sonic Adventure and Sonic Adventure DX: Director's Cut. It is fought with E-102 Gamma. To initiate the battle with E-101 Mark II, go to the Egg Carrier's Center Dome after clearing Hot Shelter. The battle takes place above the Egg Carrier's engine on a wide platform which has Rings around the center and on the edge.

Boss guide

The Mark II's most dangerous attack is nasty, but it telegraphs it by zipping backward to put some distance between it and Gamma. When the Mark II rushes forward, the player has to get out of its way by leaning hard to one side as they jump and use the Jet Booster. Avoid a direct collision, and the Mark II will continue moving to the edge of the wide platform, turning its back to Gamma. At this point, Gamma has the chance to open fire on it. Even though the player cannot hit Mark II from the front, the player can target and destroy its Guiding Missiles.

After taking two hits, the Mark II retreats to a position above the wide platform and charges up the Bomb Gun Attack, firing laser beams at the arena which cause explosions covering large section portions. After three shots, the Mark II fires the last laser of the Bomb Gun Attack, which has the largest explosion radius of them all. During this attack, the player has to keep moving, jump and use the Jet Booster to move back and forth across the area and avoid its laser beams. Eventually, Mark II returns to the arena to repeat previous attack patterns. The Mark II is finished after taking four hits.


Title Artist(s) Music Length
Crazy Robo ...Boss: E-101R Fumie Kumatani 2:33



Sonic Adventure DX - E101 mkII Speedrun in 02-E-101 Mark II Boss Battle




In other media

Sonic X

Main article: E-101 "Kai"

E-101 Mark II in Sonic X.

In the anime series Sonic X, E-101 Mark II is named E-101 "Kai". Much like in the games, E-101 "Kai" started out as E-101 Beta. When Beta failed to deliver Froggy when given this assignment by Eggman, it was discarded and send to be rebuilt into E-101 "Kai," a sight that eventually set E-102 Gamma on the path that would make it rebel against Dr. Eggman. When Gamma returned to the Egg Carrier to deactivate Beta, E-101 "Kai" appeared and engaged Gamma in combat, ignoring all Gamma's attempts to reason with it. The battle came to an end when they destroyed each other at the same time, and the bird powering E-101 "Kai" was released.

Archie Comics

E-101 Mark II fighting against E-102 Gamma, from Sonic Universe #3.

E-101 Mark II also appears in the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics, though it goes by unnamed and is just referred to as Beta.

Like in the games, E-101 Mark II started out as E-101 Beta, the first main model of Dr. Eggman's E-100 Series robots and showed much promise. Beta was created in 3235 and was assigned its first mission of tracking down Froggy by competing against his brothers to find it, but was beaten by E-102 Gamma. Instead of wasting its potential however, Beta was given upgrades to make it more powerful, turning it into E-101 Mark II, and was sent to guard one of the outposts of the Eggman Empire where it was later destroyed by Gamma.


  • E-101 Mark II is fought on the same place as Chaos 6 and ZERO.
  • Despite being renamed in the English release, the music track for E-101 Mark II is still called "ENEMY:E-101 Improved" (from its Japanese name, "E101改").
  • When Gamma discovers Beta in the process of being remodeled into E-101 Mark II, there are glowing red patches over the spots of its face where its original eyes were located. The actual model however has no actual points of removal, as E-101 Mark II's face is one large depression for its single eye to swivel back and forth between.
    • Whenever the memory of Beta's remodeling is recalled, the prerendered image lacks the glowing red patches seen during Gamma's discovery.
  • Excluding E-105 Zeta, E-101 Mark II is the only boss for E-102 Gamma who does not have a Jet Booster.




  1. Sonic Adventure online. E-102 tactical info: E-101 Beta Attack Patterns. Archived from the original on 31 May 2016.
  2. 2.0 2.1 Sonic Adventure online. E-102 tactical info: E-101 Beta Attack Patterns. Archived from the original on 31 May 2016.
  3. Sonic Adventure online. E-102 tactical info: E-101 Beta Attack Patterns. Archived from the original on 31 May 2016.
  4. Sonic Adventure online. E-102 tactical info: E-101 Beta Endurance: 4. Archived from the original on 31 May 2016.
  5. Sonic Rivals, collectible card nr. 134
  6. Stratton, Bryan (17 June 2003). "E-102 Gamma". Sonic Adventure DX: Director's Cut: Prima's Official Strategy Guide. Prima Games. p. 105. ISBN 978-0761542865.

External links

Main article | Scripts (Sonic, Tails, Knuckles, Amy, Big, Gamma, Super Sonic) | Story Screens (Sonic, Tails, Knuckles, Amy, Big, Gamma) | Credits | Glitches | Beta elements | Gallery | Re-releases (DX, 2010)