Theodore Kendris is an author notable for writing various educational books, particularly for language learning. He has a Ph.D. in linguistics and specializes in teaching English and Spanish. Kendris is perhaps best known for his work with Barron's Educational Series, a publisher that produces study guides and educational materials. One of his widely recognized contributions is to the 'Barron's 501' series, where he has written books such as "501 Spanish Verbs" and "501 French Verbs," which are comprehensive resources for language students looking to master verb conjugations and usage in these languages. His works are often used by students and language instructors as a tool for improving language proficiency.