Who played Severus Snape in 'Harry Potter and the Sorcerer's Stone'?

Who played Ron Weasley in 'Harry Potter and the Sorcerer's Stone'? In which film is Ron Weasley a character? Who played Albus Dumbledore in 'Harry Potter and the Sorcerer's Stone'? In which film is Albus Dumbledore a character? In which film is Severus Snape a character? Who played Rubeus Hagrid in 'Harry Potter and the Sorcerer's Stone'? In which film is Rubeus Hagrid a character? Who played Lord Voldemort in 'Harry Potter and the Goblet of Fire'?