In the comics and on Smallville, Pete Ross has been the best friend of Clark Kent. On television, however, Sam Jones III, who played Pete, left Smallville during its' third season. IGN has learned that Jones is coming back to the show this season, in an episode titled Hero.
Pete was a major part of the initial seasons of Smallville, and was the first person outside of Clark's family to discover Clark's secret. Pete left the show when he was "moving to Wichita", and while fans and producers have wanted to see Pete make a guest appearance, scheduling conflicts kept Jones away from the show until now.
For his return appearance, Pete is going to be exposed to kryptonite and develop superpowers of his own. It is unsure how this might affect his relationship with Clark.