Here's a very unique, and creepy, tribute to Charles Manson ... a "Helter Skelter" face tattoo made with some of the mass murderer's DNA.

Tattoo artist Ryan Almighty tells TMZ ... Patrick Boos from Niagara Falls wanted to pay homage to Manson with this not-so-subtle tattoo -- and just to ratchet things up, Patrick chose the Manson ashes option. He called it a once in a lifetime opportunity.

As we've reported, Ryan says he has ashes from Manson's cremation, and he dipped his ink gun in it while drawing a pretty intense "Helter Skelter" on Patrick's forehead last weekend.

The Beatles track from the White Album -- which dropped 52 years ago -- was written by Paul McCartney using a fairground ride as a metaphor. Manson infamously misinterpreted it as a subliminal call to incite a race war.

When members of the Manson family carried out a brutal string of murders -- including Leno and Rosemary LaBianca in 1969 -- the words "Death to Pigs," "Rise" and "Helter [sic] Skelter" were scribbled in blood at the LaBianca home.

The "Helter Skelter" forehead tattoo, Manson ashes included, set Patrick back about $500.

Remember, Almighty gave another fanboy a CM tat with the Manson ashes -- and told us he scored the macabre remains from people who scooped up ashes when they were scattered at Manson's funeral.