Technically speaking, Michael J. Fox plays seven characters. This includes doubles as a result of the time travel.
1. Marty McFly
2. Marty McFly (2015)
3. His daughter, Marlene McFly
4. His son, Marty McFly Jr.
5. The other Marty in 1955 in Part 2.
6. His ancestor Seamus McFly in Part 3.
7. And Seamus’ son William in a photograph.
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