Possible Clues:

• Roger who left 'At the Movies'
• Critic who recently lost his voice
• Flick nitpicker of note
• Roger of film reviews
• 'Your Movie Sucks' author Roger
• Roger who wrote 'Your Movie Sucks'
• Longtime partner of Siskel
• Film critic Roger featured in a 2014 documentary
• Siskel's former partner
• He once asked 'How far down can a thumb go?'