The Stalker (Ben 10)

The Stalker was a robot commissioned by Will Harangue in the episode Video Games. He recorded Ben's aliens' moves in a video game motion capture-type scanning.

History
It recorded all, but two of Ben's alien's, Way Big (being too big) and Nanomech (being too small).

While the Stalker's AI was designed to trace and destroy Ben's car. However it's not very smart, as it once accidentally attacked a minivan that looked similar to it.

The Stalker was damaged when Humungousaur used a Sumo Slammers attack, which was not recorded into the Stalker, which caused to go haywire. The defeat was followed by Nanomech, who was able to go inside it and ruin the robot's circuits in which caused it to malfunction. It was crushed by Way Big and he dropped it onto Will Harangue's car, destroying it.

Protection Against Ben's Attacks
Chemical liquid spray to kill Swampfire's plants. Multiple laser blasters. Retractable claw/tentacle. Electric antennae. Numerous missile launchers. 360 degree vision.
 * Swampfire - Fire extinguishers to put out Swampfire's fire attacks.
 * Humungousaur - Durable enough to resist damage for Humungousaur's normal attacks.
 * Spidermonkey - Immune to Spidermonkey's webs.
 * Jetray - Retractable mirrors to deflect Jetray's neuroshock blasts.
 * Cannonbolt - Can shoot strong adhesives to keep Cannonbolt in place.
 * Big Chill - Can create enough heat to melt Big Chill's ice.
 * Lodestar - Can't be magnetized.
 * Extras - Immense strength, allowing to easily overpower aliens like Humungousaur and Lodestar, as well as breaking Gwen's mana.