Melt butter in skillet over medium heat. Sauté red bell pepper, shallots, and garlic until soft. Set aside.
In a medium bowl, whisk together mayonnaise, horseradish sauce, Old Bay seasoning, and Worcestershire sauce.
Combine the mayonnaise mixture, sautéed vegetables, crab meat, egg, hot sauce, parsley, and breadcrumbs.
Use gloved hands to form 6 patties. If you feel that your patties are not solid enough, you can sparingly add a little more breadcrumbs to get them where you want them to be.
Heat olive oil in skillet over medium-high heat until shimmering. Cook patties on both sides until browned, about 2-3 minutes per side.
Drain patties on paper towels. Serve with tartar sauce.