Big Guy & Rusty, the Boy Robot started as a comic book miniseries created by writer Frank Miller and artist Geof Darrow in the mid-1990's. In 1999, the book's publisher, Dark Horse Comics, decided to get into the TV business, following industry giant Marvel in that direction. Dark Horse co-produced the Big Guy cartoon with Sony's animation arm, Adelaide, and the series was sold to Fox. Unfortunately, that was the year that Pokemon had strengthened its grip as the top cartoon on American daytime television, and Fox overhauled its lineup less than 2 months into the season, so Big Guy's 1st season was just six episodes. The series was brought back after more than a year away in January 2001 as a mid-season replacement.
At first glance, Rusty looks like he was created in the images of Alka-Seltzer's old mascot, Speedy, and the iconic mascot namesake of the Big Boy restaurant chain. He was designed to be Big Guy's successor, but isn't quite as experienced or can be entrusted to carry out an assignment solo, so Big Guy (actually a man in a suit, not quite unlike Iron Man) is brought out of retirement to mentor Rusty. Here's the open to the show. The theme song will recall some classic Japanese anime.
Since its cancellation, the series has not resurfaced anywhere, and that's a shame.