The Shadow Knight, a passion project of Ant (with help from Professor Fiction), and that Ant also calls the Stealth Knight, has amazing invisibility abilities, allowing it to completely disappear from surrounding sonar and radar for stealth missions. 

It can travel at incredible speeds (even faster than a mako shark!), and has 360° arm movement, and a nearly invisible shell when in water. Small, super-fast, and a master at disguising itself, this Knight is used almost entirely by Ant.