This question, and some of the responses to it, are a bit absurd for a couple of reasons: for one, few people outside the professional domain of cosmology and quantum gravity are even qualified to make any worthwhile assessment of Hawking’s professional accomplishments. Another is that the value of most of Hawking’s contributions are still speculative and beyond falsifications at this point, lacking any practical application in the everyday lives of the population at large; his insights my be on the right track, or may be as badly off has Huygens’ luminiferous aether. Finally, with few exeptions, scientist-celebrities are rarely known for their actual accomplishments but rather popularized because of their charmingly eccentric personalities or ability to explain phenomena.
Einstein is a premier example of the latter; I daresay that not one person out of a hundred off the street could explain for what theory Bertie was awarded the Nobel Prize in Physics, or the complete significance of Special and General Relativity, and the fact is after a few golden years he essentially contributed nothing of significance to the development of quantum mechanics or unified field theory, instead being far more effectual in the promotion of an Israeli state and proponent of world government. Dick Feynman was far better known to the public at large for being (as he described himself) “a curious character” and racounter than for his actual contributions to physics. (I’d give odds of 1:1000 that any given person could offer up a coherent layman’s explanation of quantum electrodynamics.) And perhaps the most well-known astronomer and planetologist in recent memory, Carl Sagan, actually contributed relatively little technically, his main achievements being in the popularization of the physical sciences and political advocacy of nuclear disarmament, whereas his former wife, Lynn Margulis (a name virtually unknown outside of microbiology and biochemistry circles) is virtually wholly responsible for introducing endosymbiosis, one of the most revolutionary theories in evolutionary biology and one the few legitimate challenges to modern evolutionary synthesis. Physicst Lisa Randall has made some insightful and unique contributions to cosmology and unification theory, but is probably most noted by the general public for being an attractive and articulate woman in a field dominated largely by men of peculiar habits and questionable social skills.
Even scientists who are legitimately known for real achievements have rarely performed those in isolation or exclusively; all of the components of Special Relativity were essentially in place, and had Henri Poincare been more organized, more social, and quicker on the draw he certainly would have been known as the founder of that field. Most of the hard mathematics for General Relativity was done by David Hilbert and his students. Issac Newton is most famously associated with the classical theories of mechanics and differential calculus but Gottfried Leibniz was far more accomplished in a wider array of fieldds, and ultimately more correct in concept, if less celebrated.
And there are many great scientists that do not receive wide recognition for one or more reasons: because they are not good popularizers, because their fields of research are too obscure or far afield from whatever fad pop-science culture is currently interested in, or because they just don’t seek any kind of celebrity. For what it is worth, I think that one of the smartest and most prolific guys working in gravitation today is Kip Thorne, who is at least known to attentive readers of popular science articles and books; another, virtually unknown in popular press, is James Hartle. Historically, how many people know the name of James Archibald Wheeler (one of the most prolific and influential mentors of physicists working in gravitation, atomic and subatomic physics, and quantum mechanics), J.B.S. Haldane (precursors to modern synthesis and much groundbreaking work on human physiology), or George C. Williams (evolution of sex and the gene as the fundamental unit of selection)?
This is hardly different from any other field which provides stars in popular consciousness, including acting (how many celebrities are actually great actors, and how many really great actors achieve great celebrity), politics, business, writing, et cetera? Fame is, virtually by definition, divorced from actual merit, and predicated only on the esteem that the person in question is held by the general public on the basis of some arbitrary combination of characteristics that makes the persona appealing or interesting.