Viacom Inc. was the famous American media company. Viacom was the lead distributor of CBS television series in 1970s and 1980s. Some of the famous television shows include in the syndication process are I Love Lucy, The Twilight Zone and All in the Family. Later on December 31, 2005, this corporate entity changed its name to CBS Corporation.
The logo of Viacom is quite identical to a font called Viafont. The Viafont font is a geometric sans-serif font and it was created by JHL Fonts. For both personal and commercial use, this font is free. You can download the same font for free here.
For the logo of new Viacom, the spin-off from CBS Corporation on December 31, 2005, it was probably designed based on Handel Gothic.