In a postcard-perfect little yellow house with a baby stroller on the front porch, there lives a man, his wife, three young children and about 20 elves.

The couple and their kids are friendly and well-known around the neighborhood. The elves, who aren’t always so friendly, are well-known around the world. One is so universally despised that people regularly conspire to kill him. A foul-mouthed kid just moved into the house, too, but he spends most of his time wandering around post-nuclear Washington, D.C., in a different century.

This becomes more than mildly interesting because the same elves might infest your own living room and, if not, surely they are next door or in a house just down the block. And the potty-mouthed kid is going to show up in homes all over right around Dec. 26, once Santa has completed his rounds.

Craig Sechler, nice guy from Washington, D.C., is the voice behind these and dozens of other characters in interactive video games, an intriguing, sometimes eerie, always challenging subculture that is as invisible to many people as it is all-consuming to others.

Sechler is the voice for two of the animated characters in the video game “Fallout 3.”

The game is set in Washington, D.C., 200 years after the city was devastated by a nuclear attack. Sechler, Wes Johnson and 33 other local professional voice actors took part in the production. The biggest-name voices among them are Malcolm McDowell, Liam Neeson and Ron Perlman.

Voice-over actors are a constant in modern life. They narrate documentaries, promote television shows, deliver advertising messages on radio and television, and are the voices-without-a-face on game shows. Almost every American alive has heard the booming voice of Don Pardo, but few have ever seen him.

“It’s terrific as a performer because you can play a whole lot of roles without ever looking the part,” said Johnson, 47, the voice of Mr. Burke and Fawkes in “Fallout 3.” “You know how people say, ‘You have a face made for radio?’ Well, that’s me.”

Video games present a few new twists on a profession that’s been around a least since the introduction of the Victrola. Unlike most voice work, there’s no rehearsing of lines. With so many lines to be read by a major character in a session, there’s no time for practice.

“They hand you something that’s about the size of the phone book and you spend the next four hours doing enough variations on it so that the gamers won’t get bored,” said Johnson, who is also the voice of the Washington Capitals at the Verizon Center.

Sechler, 57, claims to have the “voice of a 12-year-old,” but the truth is he can muster just about any voice he’s asked for. He is the voice — or voices — for an entire race of elves in “Oblivion,” which has a vast following. When he auditioned, Sechler found one of the elves “really annoying.”

“They said, ‘Yes, we want people to hate this character,’ ” he said.

“It’s nothing like stage acting or film acting,” said Sechler, who has done both in a career that began when he was 7 and who played the original Big Kid on the Lucky Charms cereal commercial.

Johnson said his three teenage sons take particular delight in playing “Oblivion.”

“They get to chop up Dad with a broadsword,” he said. “Not many kids can say they’ve done that.”