Mac Tonight was a mascot introduced by McDonald's restaurants in 1986. He was intended to advertise McDonald's late night hours to adults. He had a crescent moon for a head, wore a suit and sunglasses, and was depicted as being a jazzy lounge singer. The name was a play on words of the song "Mack the Knife", made popular in America by Bobby Darin. The song that played over the advertisements, called "It's Mac Tonight", was also a variant on that song, but with McDonald's-themed lyrics, such as those featured in the original 1986 commercial: ::A twinkling show, ooh -- dinner! -- out of sight ::At McDonald's (showtime), it's Mac Tonight!"

Other lyrics include this set from a 1988 commercial: ::Time to head for golden lights ::At McDonald's, it's Mac Tonight Mac Tonight is the only character in the McDonald's world to not appear in the McDonaldland advertisements.

Mac Tonight no longer appears in commercials in the United States, but pictures of him can still be seen in some McDonald's restaurants.

Talk show host Jay Leno often makes references to his likeness to Mac Tonight and promos for his show during the credits of NBC programming show his face as a moon.