Given an trivia question precisely answer the question with a word/phrase/name. External resources such as Wikipedia could be used to obtain the facts.

What fully-fledged fictional language, which has a number of typologically uncommon features, was deliberately designed to be non-human by Marc Okrand?
klingon

Who married tennis player John McEnroe in 1986?
tatum o'neal

What Greek letter is used to denote the ratio of the circumference of a circle to its diameter?

pi