The "Green Lantern" star was given the chance to reprise his role as an X-Men mutant in the spin-off in the comic book film franchise in 2009, five years after the project was first mooted.
However, the production was hit with a series of delays, including fears the script was too dark and violent, and it was only when a small sample of the intended movie was leaked online that Hollywood bosses realised the support for the film and gave it the go-ahead.
"Deadpool", due out later this year, stars Ryan as the title character and his alter-ego Wade Wilson, a cancer-stricken mercenary who becomes an indestructible mutant following a genetic experiment.