This did not fit in a comment. By popular (or at least Kevin Lin's) request, I took some photos of the IBM Mathematicians Poster on the 5th floor of the James Clerk Maxwell Building of the University of Edinburgh, just in front of the Common Room of the School of Mathematics. (My usual place of work.)

There are four photos: 1, 2, 3 and 4.

The poster only includes mathematicians who had already died at the time the poster was designed. Before the final printing other notable mathematicians who had since died were added (in name only) to the poster.

Their choice of 23 mathematicians are as follows, where I have italicised the ones who were added after the production of the poster:

• Henri Poincaré (1854-1912)
• Émile Picard (1856-1941)
• Vito Volterra (1860-1940)
• David Hilbert (1862-1943)
• Hermann Minkowski (1864-1909)
• Charles de la Vallée Poussin (1866-1962)
• Élie Cartan (1869-1951)
• Henri Lebesgue (1875-1941)
• Teiji Takagi (1875-1960)
• GH Hardy (1877-1947)
• Oswald Veblen (1880-1960)
• Emmy Noether (1882-1935)
• George Birkhoff (1884-1944)
• Hermann Weyl (1885-1955)
• Wilhelm Blaschke (1885-1962)
• Ramanujan (1887-1920)
• Thoralf Skolem (1887-1963)
• Norbert Wiener (1894-1964)
• Harald Bohr (1997-1951)
• Emil Artin (1898-1962)
• John von Neumann (1903-1957)