The Scottish singer-songwriter and actor, who rose to fame on the talent shows Popstars and Pop Idol, died at his home in the US aged 41 on 11 August.
Paying tribute to his “brother in arms”, Butler shared a photo on Instagram of the pair smiling, along with the caption: “I am devastated by the sudden passing of my dear friend Darius, a true brother in arms. My thoughts and love go to his wonderful mum and dad Avril and Booth and his two brilliant brothers Aria and Cyrus.
“To those lucky enough to have met Darius for more than a few minutes, they were deeply moved by his infectious laugh and barely containable zest for life.
“He was always armed with a smile, a booming voice, and a genuinely warm embrace that few could resist – nor would they want to!!! He was an incredible talent, a singer whose voice touched your soul and an actor with great presence.”
Butler added: “But, most importantly, he had the heart of a lion. It was bigger and brighter than the sun and an energy so contagious he could light up a room in seconds.”
The PS I Love You actor, 51, said his friend was driven to “inspire others to better themselves”.
“Our boy Darius was always constant and unwavering in his passion for life,” he said.
“But a bigger constant was his dream to inspire others to better themselves. He talked the talk but boy, did he walk the walk. He had such purity of thought, a deep wisdom and constant gratitude for people, for life, a compassion towards all.
“His hilarious self-deprecating sense of humor (he was funny as s***) allowed him to stay humble – something he valued deeply. Darius’s undying commitment to being of service to individuals – his family, his friends (none more so than me) and to the world at large made him the perfect friend.”
Danesh first earned fans for his theatrical cover of Britney Spears’s “Baby One More Time” on 2001 talent show Popstars.
In 2002, Danesh came third on Pop Idol behind Will Young and Gareth Gates. His memorable moments on the show include his renditions of Tom Jones’s hit “It’s Not Unusual” and Atomic Kitten’s “Whole Again”. The final was watched by more than 13 million viewers.
Gates also shared an emotional tribute on Instagram, remembering Danesh as “one of the most beautiful, intelligent and gentle souls I was lucky enough to know, a soul that lit up every room”.
Having turned down a record deal from judge Simon Cowell, Danesh nevertheless reached number one in the UK after Pop Idol ended with his track “Colourblind”. His album Dive In reached the top 10.
He became a West End star, appearing in musicals such as Chicago and the Oliver Award-winning Guys and Dolls.