The E-1000 was a mass-produced variant of the E-100 Series robots, armed with two arm cannons.
Eggman seems to have created the E-1000 with guard duty in mind, as he deployed them as such in multiple locations during his bid to seize control of the Eclipse Cannon. Sally, Antoine and Tails encountered one of these robots while searching for a Chaos Emerald in the Crystal Cave. The robot proved no match for the trio. (VG: SA2/SA2:B; StH: #261, #262)