Yulian Semyonovich Semyonov (Russian: Юлиа́н Семёнович Семёнов, pen-name of Yulian Semyonovich Lyandres (Russian: Ля́ндрес) was a Soviet and Russian writer of spy fiction and detective fiction, also scriptwriter and poet.

The father of Semyonov was Jewish, the editor of the newspaper “Izvestia”, Semyon Alexandrovich Lyandres. In 1952 he was arrested as "an accomplice of the Bukharin counterrevolutionary conspiracy" and severely beaten during the interrogations; he became partially paralyzed as the result. His mother was Russian, Galina Nikolaevna Nozdrina, a history teacher.

His wife Ekaterina Sergeevna was a step-daughter of Sergey Vladimirovich Mikhalkov (the wedding took place on 12 April 1955). Though their family life was quite complicat