Guardians of the Galaxy director James Gunn has unveiled a new picture of Karen Gillan as Nebula, Digital Spy reported.

The Doctor Who star plays the alien villain in the upcoming Marvel movie, and was first glimpsed in the official trailer released last month.

Gunn posted the image on Instagram, describing Nebula as the movie's "interplanetary Clint Eastwood".

Gillan, who shaved her head to play the role, has previously expressed an interest in appearing in a crossover with The Avengers.

Chris Pratt, Zoe Saldana, Dave Bautista, Benicio Del Toro, Lee Pace, Michael Rooker, Peter Serafinowicz and Glenn Close will also feature in the cosmic movie.

Guardians of the Galaxy is released on August 1 in the UK and the US.