Einstein was unable to talk until he was four years old and could not read until he was nine. Teachers considered him to be mentally deficient, unsociable and a dreamer. He failed the entrance examination for college. He would become arguably the world’s most famous physicist after developing the theory of relativity.
Source: Graham,J., Shinkfield, A., Smith, K. & Polzin, U., 'Employer benefits and costs of employing a person with a disability', Journal of Vocational Rehabilitation, vol. 17, pp. 251-263.