A version of Marty McFly once visited the Brick Boulevard, Diagon Alley, and the Land of Ooo in various universes.
Biography
McFly was standing in the Brick Boulevard when the Twelfth Doctor, Doc Brown, and Peter Venkman crashed their vehicles into each other, winding up in a wreck. (WC: Doctor, Doctor, Doctor [+]Loading...["Doctor, Doctor, Doctor (webcast)"])
Later, he visited Diagon Alley, and jumped out of the way as Wyldstyle sped towards him on a motorcycle. He later charged into battle alongside several other individuals in the Land of Ooo, before winding up in a mosh pit with the rest of the battle's participants. (WC: New Adventures Await! [+]Loading...["New Adventures Await! (webcast)"])
Behind the scenes
In non-valid sources
Marty McFly once played his red guitar, causing the Wicked Witch of the West to fall off of her broom. He later played it next to the DeLorean time machine. (WC: Endless Awesome [+]Loading...["Endless Awesome (webcast)"])
Other matters
Marty, along with his Back to the Future costar Doc Brown, appears as a playable character in LEGO Dimensions [+]Loading...["LEGO Dimensions (video game)"].