Thyroid eye disease (TED), also known as “thyroid-associated ophthalmopathy or orbitopathy” (TAO), is an autoimmune disorder of the extraocular muscles and surrounding orbital connective tissue. It is usually associated with Graves’ disease, affecting approximately 25% of these patients, but can also be associated with Hashimoto’s thyroiditis occurring in nearly 6% of those patients. TAO may occur simultaneously with the manifestations of hyperthyroidism or later (approximately 70%), before the manifestation of hypothyroidism (approximately 25%), in the euthyroid state (<5%) and in hypothyroidism (3–5%). Ocular lesions in autoimmune thyroid diseases occur five times more often in women than in men; however, their course and prognosis are so far worse in men. Although the pathophysiology of TAO remains unclear, sensitized T-cells and autoantibodies against thyroid-stimulating hormone receptor (TSH-r) located on thyroid cells (thereby stimulating excess production of thyroid hormone), orbit muscles, and fibroblasts are targeted in patients developing ophthalmopathy. They may trigger an inflammatory process in the orbital tissues. As a result, leukocytes secrete cytokines, which stimulate fibroblasts to secrete and accumulate glycosaminoglycans, resulting in the swelling of extraocular tissues. There are two distinct stages of the disease, an active inflammatory stage followed by an inactive quiescent stage. There are no effective means of preventing the disease or reliably altering its course. Current therapeutic options include local supportive measures, corticosteroids, external beam radiation, and steroid-sparing immunosuppressive agents for reducing the inflammation during active disease, and surgery for correcting the residual abnormalities secondary to fibrosis in the inactive state of the disease. This chapter discusses the prevalence, pathogenesis, clinical implications, assessment/diagnosis, and treatment of Hashimoto’s ophthalmopathy. It also addresses the novel therapeutic options and future therapeutic strategies, as well as the role of artificial intelligence (AI) in TED regarding diagnosis, disease monitoring, and decision-making. This chapter will be a great tool for clinicians to better understand TED and provide an outlook on future perspectives.