One senses mortality throughout “The Serial Portrait: Photograph and Identity in the Last One Hundred Years.” The National Gallery of Art exhibition traces a practice mostly peculiar to photography: the creation of multiple images of the same person, often self-portraits, tracing changes in identity that occur naturally over time or through manipulation of self-expression. In the first room of the show, male photographers focus on the female form, often their wives or paramours, producing visual essays that inevitably track the effects of aging. In later rooms, the serial photography project grows more experimental, more a question of identity, manipulations of gender and class. But death is always around the corner.

Nicholas Nixon’s “The Brown Sisters” dominates an entire wall, and, although full of life, the work leaves one with a shudder. An ongoing project, this collection of 37 prints documents the photographer’s wife and her three sisters in photographs made each year since 1975. Displayed in a grid of four rows, the photographs offer without comment what seems a miracle: a sustained communion among four sisters over almost four decades. But the lowest row, only seven photographs long, is terrifying. Will it be completed? When will this group of four be a group of three, then two, then one? What is the end of this project?

There’s only one end, and it’s a certitude, of course. The Nixon series, presented with three missing photographs on the lowest row, projects death into the present, into the midst of life, reminding one of Roland Barthes’s observation: “Whether or not the subject is already dead, every photograph is this catastrophe.”

As you prepare to leave the exhibit, death returns in the form of an image that seems to be a giant reproduction of Robert Mapplethorpe’s last self-portrait, made a year before the photographer’s death from complications arising from AIDS in 1989.

Mapplethorpe is seen facing the viewer square on, holding a walking stick topped by a metal skull. It is an “in your face” image, death personified, made all the more disturbing by a small anomaly around the eyes. This is not, in fact, Robert Mapplethorpe, but one of a series of self-portraits by the British photographer Gillian Wearing, who photographed herself wearing a freakishly accurate Mapplethorpe mask. Wearing reproduced all the essential features of the iconic original, but you can still see a set of unfamiliar eyes staring out from the eyeholes of the silicone mask. She is, literally, inside of Mapplethorpe’s face.

By bringing death back in the form of Mapplethorpe’s provocative image, curator Sarah Kennel tightens the show’s meaning. The Mapplethorpe impersonation gives the viewer license to reflect on death and loss when looking at many of the photographs. And it connects what seem, frequently, to be two very different kinds of projects on display: photographs about time and photographs about categories and boundaries.

Alfred Stieglitz’s portraits of his lover and then wife, Georgia O’Keeffe, were both an exercise in form and a publicity project, fashioning O’Keeffe into his idea of the feminine sex-symbol artist. In a 1918 portrait, the young O’Keeffe is seen lounging in bed, pulling seductively at the strap of her lingerie. It’s fashionable to look for signs of resistance in O’Keeffe’s response to the lens: In 1930, photographed in front of one of her paintings, she is older, wiser, more self-possessed and less interested in being sexually open to the camera. But even in a 1919 print, “Georgia O’Keeffe — Hands and Thimble,” you sense something delicately truculent: The thimble, a tiny bit of silver on the middle finger of one hand, functions as a mask of sorts, like a tiny falconry hood pulled over one beautifully tapered digit.

Work by Harry Callahan, who photographed his wife, Eleanor, frequently in the 1940s and ’50s, and by Callahan’s protege Emmet Gowin, whose wife, Edith, is seen in work from the 1960s until the present decade, feels more intimate, honest and respectful than Stieglitz’s. The Callahan images are bit too familiar at this moment, having appeared in a National Gallery retrospective of Callahan’s work less than a year ago. But the Gowin photographs are a delight, both playful and formally inventive. In two images, made four years apart, an older but still handsome Edith is seen dressed in black, wearing age proudly; nearby, an image made at night as moths swirled about her, seems to channel some immanent and preternatural youth, with Edith’s head surrounded by a halo of light.

The fundamental gloominess inherent in so many serial photographs may explain why later photographers have turned to other forms of seriality, other variations of the self to document. Milton Rogovin’s photographs of ordinary and often impoverished people focus on self-presentation, the difference between a man dressed for his grungy day job and a man seen at home, surrounded by the things that make him feel self-possessed, worldly and rich. Narrative inevitably creeps into serial photographs. Both Andre Kertesz’s photographs of his vibrantly youthful brother Jeno and Lee Friedlander’s photographs of himself feel a bit like film stills, without captions or storyboards to give them definite coherence.

More volatile and sometimes problematic are the postmodern games of identity that dominate much of the last two rooms in the exhibition. Nikki S. Lee’s impersonations of subcultural identity are slick and repellent, the worst sort of empty art game — her superficial dress-up as a skateboarder or yuppie is derivative and says nothing about the people whose identities she mimics. Vibeke Tandberg’s “Faces” series from 1998 is equally centered on the self, but it is far more meaningful and touching. Using digital techniques to morph her image with those of people who are important to her, Tandberg produced 12 closely related variations on herself, many of them enticingly androgynous. Yet the results, which invite the viewer to seek small variations — moles and crow’s feet and shadows of beard — are far less narcissistic than Lee’s work. Tandberg’s game with her image is ultimately about the powerful impact of tiny markers of identity, gender and race, the superficial clues with which we all too quickly sort people into categories. The number 12 also suggests a kind of musical project, equal tones, open to rearrangement and interpretation.

All of this leads to Wearing’s large-scale impersonation of Mapplethorpe, which confronts the departing viewer rather like one’s image in the mirror. The allure of the narcissistic gaze never goes away, somehow promising us insight into who we are. But it isn’t necessarily self-love that grips us. Rather, the face is the closest and most familiar physical thing through which we can seek basic information about life: about who we are, what we are feeling, how old we have become. It’s no wonder photographers have returned to it again and again, trusting it implicitly as a map of the self or doubting it, like Wearing and others, as merely a mask or a put-on. In the end, the face’s ambiguities are unresolved, its potential for meaning dissipated, leaving others, through photography, to read it or not, and likely to find just as little resolution to the mystery.

The Serial Portrait: Photographyand Identity in theLast One Hundred Years

opens Sunday and is on view through Dec. 31 in the West Building of the National Gallery of Art, Fourth Street and Constitution Avenue NW. 202-737-4215.