World Canonical Texts
Just looked at its index, and see what people's names are mentioned in many pages. Included are those that the index shows 10 or more pages. Some page count are replicated - I didn't eliminate. And as in most index, the accuracy is questionable.
81 Freud, Sigmund
42 Eliot, T.S.
40 Wittgenstein, Ludwig
33 Picasso, Pablo
30 Schoenberg, Arnold
29 Einstein, Albert
27 Darwin, Charles (19th c.)
27 Russell, Bertrand
27 Sartre, Jean-Paul
22 Heidegger, Martin
22 Keynes, John Maynard
22 Galbraith, John Kenneth
21 Orwell, George (Eric Blair)
20 Planck, Max
20 Stalin, Josef
19 Rutherford, Ernest
19 Hofmannsthal, Hugo von
19 Riesman, David
18 Bergson, Henri
18 Husserl, Edmund
18 Mann, Thomas
17 Marx, Karl (19th c.)
17 Mead, Margaret
17 Boas, Franz
17 Strauss, Richard
17 Bell, Daniel
16 James, William
16 Bohr, Niels
16 Hayek, Friedrich von
16 Marcuse, Herbert
16 Levis, F.R.
16 Trilling, Lionel
15 Nietzsche, Friedrich (19th c.)
15 Weber, Max
15 Stravinsky, Igor
15 Friedman, Milton
15 Jung, Carl Gustav
14 Joyce, James
14 Woolf, Virginia
14 Arendt, Hannah
13 Kafka, Franz
13 Benedict, Ruth
13 Morgan, T.H.
13 Schnitzler, Arthur
12 Beauvoir, Simone de
12 Spengler, Osward
12 Fromm, Erich
12 Lewis, Sinclair
12 Williams, Raymond
11 Lacan, Jacques
11 Chadwick James
11 Beckett, Samuel
11 Brecht, Bertolt
11 Rorty, Richard
11 Lawrence, D.H.
11 Whitehead, Alfred North
11 Popper, Karl
11 Levi-Strauss, Claude
11 Lysenko, Trofim
11 Mannheim, Karl
11 Wilson, Edward
10 Braudel, Fernand
10 Chomsky, Noam
10 Heisenberg, Werner
10 Hemingway, Ernest
10 Conrad, Joseph
10 Adorno, Theodor
10 Auden, Wystan Hugh
10 Dawkins, Richard
10 Baldwin, James
10 Rosenberg, Alfred
Bolded are the top-mentioned once (20+) who are in the field of humanities / social sciences. Didn't include Russell since Watson's book treat him mostly as mathematician. Thinking more about it, I did not include Adam Smith in my list of 150 - and I only included Marx not for his economics but because of his (political) philosophy, sociology and theory of history. So mostly likely Keynes and Galbraith will be out also ... but then should Freud be included? Anyway, based on Watson's view, and based on my criteria of inclusion - the top candidates are Freud, T.S. Eliot, Wittgenstein, Sartre, Heideggar, Orwell. Not that surprising - always know that Freud is around the corner, and 20th c. philosophy if there are 2 inclusions it would have been Wittgenstein and Heideggar even without referring to Watson. I always feel dislike and the fleeting nature of influence of existentialism. T.S. Eliot is canonical, but without Watson I would not put him so clearly ahead of say James Joyce, Kafka, Proust, Beckett or Wolff. Orwell is a little surprising.