In a large pot, combine the ground beef, diced tomatoes, Rotel, corn, beans, taco seasoning, and ranch dressing packet. DO NOT DRAIN any of the canned goods.
Bring soup to a boil over medium to medium-high heat. Once boiling, simmer soup for 30 minutes.
Serve with shredded cheddar cheese, sour cream, green onions, and/or tortilla or corn chips.
If making in a slow cooker; combine all of the ingredients and heat on low for 3-4 hours.