Yury Nikulin, Russia's most popular actor and a beloved figure whose face is known by Russians of all ages and social classes, died Thursday at the age of 75 at a Moscow clinic. Nikulin suffered heart failure during an Aug. 5 heart operation at the Center for Endocrine Surgery and Lithotripsy in eastern Moscow. Since then, the country watched and waited as doctors attempted to save his life. Thousands of people, from unknown admirers to President Boris Yeltsin, called to find out about his health, and his condition was reported by news media every day. A former clown in the Moscow Circus, he starred in two of the Soviet era's funniest and best-loved movies, ""Brillyantovaya Ruka"" (The Diamond Arm) and ""Kavkazskaya Plennitsa"" (Prisoner of the Caucasus). Nikulin's unpretentious figure was unique because it was absolutely typical.