Demis Roussos, who rose to fame as part of Greek prog band Aphrodite's Child before embarking on a hugely successful solo career, has passed away at the age of 68.

Formed in 1967 as a quartet that included Roussos and synth pioneer Vangelis, Aphrodite's Child found immediate European success with their first LP, scoring a hit single with 'Rain and Tears,' a song musically inspired by Pachelbel's Canon in D major. They branched out quickly, delving into an array of other styles for 1969's 'It's Five O'Clock' album, and then spent two years working on their third album, the double LP '666.'

Sadly for the group's growing fan base, tensions between the band members proved too difficult to overcome, and by the time '666' came out in June of 1972, Aphrodite's Child had already split, freeing Roussos and Vangelis to pursue solo careers that -- while widely divergent in terms of style -- both eventually overshadowed the band's success.

The son of a classical guitarist and a singer, Roussos started studying music at the age of 8, eventually completing his course of education at an Athens university. Although he was arguably best known for his singing, he was also an accomplished instrumentalist; during his stint with Aphrodite's Child, he contributed trumpet, double bass, organ and bouzouki.

Between 1971 and 2009, Roussos released dozens of solo albums, and while much of his success was regional, he continued to enjoy a chart presence across Europe and the U.K. while touring the globe and entertaining crowds with a personality as imposing as his frame. "I have a very different personality from a crooner. I'm not Tom Jones! Or Engelbert Humperdinck or Frank Sinatra. It is very, very easy to see what these people are. Their image is very definite," Roussos once mused. "I am much, much deeper. But ... I don't want to find out what it is because if I find out what it is, if I discover why there's all this mystery, then -- no more Demis Roussos!"

Classic Rock Magazine reports that Roussos passed away on Jan. 25 after being admitted to Ygeia Hospital in Athens. The news has been confirmed by Roussos' daughter, although the cause of death has not been publicly shared.

"Some people sing and it's important what they say. But for me there is no message. There's nothing. Because I have a voice. Which is the voice. I can guarantee you that I have a voice that nobody in the world has," Roussos told Melody Maker in 1976. "It's not the best voice in the world, but it is unique."

Rock's Tragic '27 Club'

See Rockers We've Lost in 2015