Chavez died of cancer Tuesday. He was 58.
"Today the people of the United States lost a friend it never knew it had. And poor people around the world lost a champion," Penn said in a statement to The Hollywood Reporter Tuesday. "I lost a friend I was blessed to have. My thoughts are with the family of President Chavez and the people of Venezuela. ... Venezuela and its revolution will endure under the proven leadership of Vice President Maduro."
"South of the Border" writer-director Stone also issued a statement to the entertainment industry trade newspaper.
''I mourn a great hero to the majority of his people and those who struggle throughout the world for a place," Stone said. "Hated by the entrenched classes, Hugo Chavez will live forever in history. My friend, rest finally in a peace long earned."