During the late seventies and early eighties, a large number of arcade games from various companies used this 8 × 8 font :
Many used it but someone must have invented it. Who and when ? The oldest occurrences I've found are in the 1976 Atari games Cannonball and Sprint 2. Atari used the font again in 1977 in Canyon Bomber, Destroyer, Dominos, Sprint 4, Subs and Triple Hunt. In 1978, it was used on all the games Atari released that had an 8 × 8 font.
The first non-Atari game to use it appears to be Namco's Gee Bee in 1978. In 1979, Namco used it again for Bomb Bee, Cutie Q (mix of 6x8 and 8x8) and Galaxian. The same year, the font spread to other companies : Irem (Andromeda and Space Beam), Nichibutsu (Rolling Crash/Moon Base) and Nintendo (Sheriff).
Since Atari apparently was its first and, for several years, only user, it could have been designed there, possibly by the authors of Cannonball or Sprint 2. According to Alexis Bousiges' history.dat, Cannonball was written by Owen Rubin and Sprint 2 by Dennis Koble and Lyle Rains.
The Arcade history page on Sprint 2 states
believed to be the
first game to utilise the now well-known 'arcade font'.
This is http://www.teaser.fr/~amajorel/arcafont/, last modified AYM 2011-01-14.