Isaac Clarke may refer to:

• Isaac Clarke (Dead Space), the main protagonist of the Dead Space series
• Isaac Clarke (publisher) (1824–1875), Welsh newspaper proprietor, printer and publisher

• Undertown (comics)
• Undertown (manga)
• Undertow (The Wire episode)
• Undertow (water waves)
• Under trial
• Under Two Flags
• Under Two Flags (1916 film)
• Under Two Flags (1922 film)
• Under Two Flags (disambiguation)
• Under Two Flags (novel)
• Undertype steam wagon
• Underutilised crops
• Underutilized crops
• Underutilized Crops
• Under vehicle inspection
• Undervoltage-Lockout
• Undervoltage-lockout
• Undervotes
• Undervoting
• Underw.
• Under water
• Underwater!
• Underwater acoustic beacon
• Underwater acoustic communication
• Underwater acoustic positioning system