Old Faithful is a geyser within Yellowstone National Park.

Old Faithful may also refer to:

• Old Faithful (film), a 1935 film
• "Old Faithful" (rugby league song)
• "Old Faithful" (Hope & Faith episode)
• "Old Faithful", a 1934 short story by Raymond Z. Gallun
• "Old Faithful", a 1955 story from The Railway Series book Four Little Engines
• Old Faithful, Graeme Obree's bicycle

• Old Faithful Historic District, a historic district in Yellowstone National Park
• Old Faithful Inn, a hotel in Yellowstone National Park
• Old Faithful of California, a geyser near Calistoga, California