Charlie Manson and his Susan Atkins look-alike gal pal plan to tie the knot behind bars and live creepily ever after.

“I’ll tell you straight up, Charlie and I are going to get married,” Manson’s 25-year-old girlfriend, “Star,” tells Rolling Stone.

“When that will be, we don’t know. But I take it very seriously. Charlie is my husband,” she said.

If the 79-year-old mass killer wants to take a wife, the only thing stopping him is cold feet.

California prison rules ­allow inmates to marry anyone but a fellow inmate in the same institution.

Manson has spent 44 years in prison, including the last 15 at the state prison in Corcoran, ­for the grisly 1969 murders of actress Sharon Tate, her unborn baby, her guests and other victims.

Atkins, a blond member of the “Manson family” that carried out the bloody slayings, died in prison in 2004.

“Star,” who has lived in Corcoran for seven years, has become Manson’s most loyal supporter.

“People can think I’m crazy,” she said. “But they don’t know. This is what’s right for me. This is what I was born for.”