One of the big jokes in Catch-22 is Major Major's striking resemblance to Henry Fonda. Why did Joseph Heller choose Henry Fonda in particular? Is there any significance to the choice, or was it a somewhat arbitrary choice of someone that the audience was likely to have seen (or at least heard of) before?
From Containment Culture: American Narratives, Postmodernism, and the Atomic Age, by Rensselaer Polytechnic Institute Professor of Literature Alan Nadel:
If the authority for offices of command relies on null sets, perhaps the exemplary null set in the novel is Major Major Major Major. Even his name is an empty sign, signifying not authority but the name of authority, not power but its absence. His promotion to squadron commander was rendered as a tautology that emphasized its insignificance: "'You're the new squadron commander,' Colonel Cathcart had shouted rudely across the railroad ditch to him. 'But don't think it means anything, because it doesn't. All it means is that you're the new squadron commander'" (57). [...] Bearing a striking resemblance to Henry Fonda, Major Major even lacks his own physical identity and is recognized only as a reference point, an allusion to someone he is not and whose public identity, in turn, is an imaginary referent, coming as it does from roles written and directed by other people.
From Philip D. Beidler, "Mr. Roberts and American Remembering; or, Why Major Major Major Major Looks Like Henry Fonda", Journal of American Studies 1996, 30(1), pp. 47-64:
Major Major Major Major, the ultimate product of and operational cog in the Catch-22 machine. He is the definitive good Joe in a bad situation.
From Jerry M. Lewis and Stanford W. Gregory, "Extensions to the sociology of the inept", Qualitative Sociology 1978, 1(1), pp. 58-78 (relating Catch-22 characters to William J. Goode's sociological definition of ineptitude):
The clearest portrayal of an inept role is the character of Major Major Major Major. [...] We see in Heller's depiction of M several dimensions of ineptness. First, he always followed the rules yet no one liked him or trusted him. [...] Second, there is a clear foreshadowing of the well-known "Peter Principle": that one tends to rise in organizations to one's own level of incompetence. [...] A third dimension of M's ineptness is related to his physical appearance. He felt he must continually apologize for the fact that he was not Henry Fonda, for it was anathema to him being so closely identified with competence. After several of these "embarrassing catastrophes" M begins to take an active part in defining himself as inept. [...] Finally, Heller (1955:104) writes: "In the midst of a few foreign acres teaming with more than two hundred people, he had succeeded in becoming a recluse."
From the satirical depiction of M we can derive this general proposition: that over a period of time the inept become aware of their role, and when they accept it begin to actively contribute to its institutionalization. Thus, Heller in his depiction of M moves the analysis of the inept beyond Goode's model, because he allows the individual to have an active part in the definition of the inept role. In Goode's treatment the inept can do little but accept their fate. Heller, though, argues that when the inept, as personified by M, knowingly accept their roles, they begin to develop through interaction the range and definition of that role. Thus, we see M, after a combination of events, working "creatively" to develop his role as an inept officer.
There is, in fact, a deliberate irony here I think: Henry Fonda was famous for his competence, Major Major's claim to fame is... his resemblance to Henry Fonda, which drew unflattering comparisons.
Long before he even suspected who Henry Fonda was, he found himself the subject of unflattering comparisons everywhere he went. Total strangers saw fit to deprecate him, with the result that he was stricken early with a guilty fear of people and an obsequious impulse to apologize to society for the fact that he was not Henry Fonda.
The other irony is that the sheer absurdity of the "inverted" system he found himself in. Major Major was notable for his mediocrity in spite of having apparently been at least a reasonably good student. He drew unfavorable comparisons to Henry Fonda because he looked like him (in spite of Henry Fonda's popularity and competence). He was reasonably well-liked and accepted by his peers when he joined the military until he was promoted to squadron commander, at which point people wanted nothing to do with him anymore. And, as Squadron commander, he kept getting forced to re-sign the same purely informational (or even contradictory) papers when he signed with his real name, and he stopped getting them back when he signed them with the fake name "Washington Irving." He was also promoted to a Major in the first place by accident due to a computer glitch.
So, people's reaction to his resemblance to Henry Fonda (as well as the irony of a mediocre character resembling a notably competent and "good-looking" individual) is all part of the absurdity of the situation he finds himself in.