The Joker

The Joker was an enemy of Batman.

Biography
The Joker was present when the Twelfth Doctor, Peter Venkman, and Doc Brown crashed into each other on the Brick Boulevard, laughing as a wheel bounced past him. (WC: )

Behind the scenes
The Joker was a major antagonist in LEGO Dimensions, and originates from the DC Multiverse.

The Joker is depicted in the front cover of Detective Comics #566, which appeared in, although his appearance cannot be seen in the episode due to the cover being partially obstructed.