B4 was a government agency tasked with investigating and countering alien activity on Earth in the Walkyverse. Though never referenced in It's Walky!, B4 was intended to play a pivotal role in the abandoned It's Walky!: Resurrection game.
Its exact dates of operation are unknown, but it was active at least as early as July 1947, and was apparently eliminated sometime prior to the time period during which Anthony McHenry and Linda Mitchell carried out anti-alien similar missions.
No details of any B4 operation have been revealed, but the agency maintained a facility at the infamous Area 51 in Nevada. This facility, although abandoned, remains under guard.