Johnny Dark is an American comic with many past appearances on television, nowadays appearing on CBS’ Late Show with David Letterman, doing a comic spot as the oldest page at CBS (serving an extraordinary 39 years when a normal page's career lasts not much longer than a year or so). He presents an abrasive, more than sarcastic character who pities himself for the career he has led at CBS; in his own words, he's "livin' the freakin dream." Johnny is apparently a recovering alcoholic and enjoys cigarettes, and is known to use profanity much to the "shock" of Letterman. Johnny has displayed the possession of an imaginary horse which apparently is hard to control, as he goes careering around the stage of the Ed Sullivan Theater, and even on one occasion, onto the rain soaked streets of New York City right before cutting to commercial. In a vacuous attempt to add to his prestige and seriousness, Johnny added shoulder-pads reminiscent of a movie theater usher to his costume (which later vanished), and has broadcast spoofs of Andy Rooney's 60 Minutes pieces, entitled, A Moment with Johnny Dark.

In mid-August 2006, Johnny started appearing in brief vignettes while Dave performed his monologue, performing the following various skits (in chronological order):

• a FBI agent, frisking Letterman (crotch and all), then quipping: "Wow, you're not packing anything!";
• as a stage manager, prepping Letterman the seconds before air time, and then patting his rear;
• dressing as a band performer, and goading on Paul Shaffer and the CBS Orchestra to "get this party on," and attempting to play the trumpet, but failing miserably, leaving the stage with a declaration of "ah screw it;"
• walking out on stage and peering into the audience, and then declaring, "Gee it's so quiet out here I thought the audience left!" Letterman laughed, but the audience jeered (all in good fun);
• coming out in a casual suit outfit and scoping the scene, noting how the CBS Evening News had made a great deal of changes, yet on Letterman's show, it's still "the same old crap";
• dressed in surgeon's clothing, looking at his watch, then declaring, "Let's call it 11:36 - the exact moment the show started going to Hell";
• coming out with a sign that reads, "Needs Mets tickets," looking sadly at the audience in hope someone would help him out, but after having none given to him, is told to "Get out of here" by Letterman;
• trying to "change" Letterman via a remote control, then tossing it to the floor in disgust uttering "Piece of crap!" in dismay for its failure to work.
• pretending to be a tailor, and attempting to measure Letterman's inside leg, "accidentally" bumping into Letterman's privates while doing so, and then pulling the measuring tape back, muttering, "Nothing!";
• carrying a clipboard and stating he was doing an office pool, asking Letterman whether the show would either "suck" or "blow;" Letterman was not decisive, so Johnny said he would put him down for "suck."
• dropping an opened, half-empty bag of Doritos on Dave's desk, uttering, "I'm your Secret Santa."

Johnny Dark is also a Historian. His multipart series, "Johnny Dark's Lincoln", can be viewed online via his Myspace page. He also appears on the show as Mark Twain and also as his brother Johnny Twain.

Johnny Dark has also made appearances on the Donny and Marie show in Skits such as "Sludge" and "the Dungeon"