Stephan Shelanski, Starz’s exec veep of programming acquisitions, is stepping down from his post at the end of the year.

“After more than 18 years at Starz I have decided to leave the company,” Shelanski informed colleagues in an internal memo circulated at the paybler. “I’ve worked at only two companies in my entire career, HBO and Starz, and now is an ideal time to explore new challenges and opportunities. … Starz has enabled me to grow in my professional career.”

Shelanski will remain on board at the company until the close of 2012 to “help with the transition and work to close ongoing deals.”

“From developing our long-term output deals, to launching compelling original series like ‘Party Down’ and ‘Spartacus,’ Stephan was instrumental in the growth and success of the Starz and Encore networks,” Starz CEO Chris Albrecht said in a statement “While Stephan will certainly be missed by me and the entire Starz Family, we wish him the best as he moves into the next phase of his career.”