Malbolge was invented in 1998 by Ben Olmstead. This esolang is considered to be the most complicated programming language.
INTERCAL
Jim Lyon and Don Woods developed INTERCAL in 1972 as a parody of the various programming languages. INTERCAL has many features designed to make it frustrating for the programmer.
Whitespace
Whitespace was developed at the University of Durham by Chris Morris and Edwin Brady. The language was released on April fools day of 2003. The entire language depends on space, tab, and linefeed for writing any program.
Brainfuck
Brainfuck was developed by Urban Muller in 1993. The language was invented as an amusement for programmers. The name suggests that the language is difficult for any programmer to comprehend.