Robert Marlow is the former "Accounts Man" of the Springfield Nuclear Power Plant.
Homer replaced him when Robert retired from his job. The job had cost Marlow his family, secret other family and he missed his family's important events. He became addicted to martinis and drank a lot of Bourbon.
He taught Homer the ways of an accounts man after he retired. When Homer and his family go rafting down the Rattler River Canyon, Homer invites the nuclear regulators along with Mr. Burns. As their raft goes over the falls, Marlow saves Mr. Burns from falling and Homer gets his old job back.