Charlie Sheen celebrated his 51st birthday with his ex-wife Denise Richards.

Charlie Sheen (Instagram)

Charlie Sheen (Instagram)

The Hollywood actor marked his big day by spending it with the actress and their girls, 12-year-old Sam and 11-year-old Lola, as well as Denise's adopted daughter Eloise and his friend Tony Todd.

The former 'Two and a Half Men' star - who revealed he is HIV-positive in 2015 - took to Instagram to share a picture of the group posing in front of a plane and captioned it: "The birthday bunch."

Todd tweeted the same photograph and said: "Epic night celebrating [Sheen's] birthday with the family at Macklemore concert."

Earlier, the group had attended the Macklemore and Ryan Lewis' show at the Bumbershoot festival in Seattle, Washington, where the actor was invited up onto the stage by the rap duo.

The harmonious relationship between Charlie and Denise, who were married from 2002 until 2006, is a marked contrast to the situation earlier this year, when she filed a lawsuit against her ex-husband, claiming he was no longer honouring a trust that guaranteed her and their kids had a home and financial security.

Prior to that, the pair split in 2005, with Denise accusing the Hollywood icon of alcohol and drug abuse and threats of violence.

And following their divorce in November 2006, they became embroiled in a custody dispute over their two daughters.

However, Charlie and Denise now appear to have mended their relationship, with the actor recently sharing an adorable picture of himself, his ex-wife and their girls.

The controversial actor captioned the casual snap: "A gaggle of awe sum!! (sic)"