A Bottom Round Roast (or Round Rump) makes this meal affordable, the packaged gravy mix makes it easy to prep, and all those hours in a slow cooker make it fall-apart tender.
Prepare pot roast vegetables: cut potatoes in half (or into quarters if large), onions into 1/2-inch wedges, and carrots and celery into 2-inch pieces; set aside.
Combine gravy mixes, flour, salt and pepper in large bowl. Add vegetables to bowl; toss to coat well. Remove vegetables from flour mixture and place in 5 to 6-quart slow cooker. Add beef pot roast to bowl, turning to coat evenly with flour mixture. Remove pot roast and place in slow cooker in center of vegetables.
Whisk beer into remaining flour mixture until smooth; add to slow cooker. Cover and cook on HIGH 6 to 7 hours or LOW 9 to 10 hours or until beef and vegetables are fork-tender. (No stirring is necessary during cooking.)
Remove pot roast and vegetables. Skim fat from gravy. Carve roast into thin slices. Serve with vegetables and gravy. Sprinkle with parsley, if desired.