Sergey Alexandrovich Alexeyev (Russian: ?????´? ??????´??????? ??????´??, 26 September 1868, Kazan, Imperial Russia, — 5 December 1922, Yalta, Soviet Russia) was a Russian playwright, better known under his pen name Naydyonov (????????), another one being Rogozhin (???????).
His debut play, the semi-autobiographical Vanyushin's Children (Deti Vanyushina, ???? ????????, 1901) proved to be his most famous one and is considered part of the classic Russian drama legacy.
It earned him the Griboyedov Prize which he shared that year with Maxim Gorky (The Philistines) and Vladimir Nemirovich-Danchenko (In Dreams).
His other notable plays include The Life of Avdotya (Avdotyina zhizn, ????????? ?????, 1904), praised by Maxim Gorky and Walls (Steny, ?????, 1907).