Also invited is infielder Jason Smith, who accepted an assignment to Omaha after clearing waivers. Smith was Pena's primary backup in the second half last season.
Two players signed on Thursday to Minor League contracts also were invited: Outfielder Damon Hollins and catcher Ken Huckaby.
Hollins, 33, played last season with the Yomiuri Giants in Japan. A right-handed batter, he's played in 256 big league games with the Braves, Dodgers and Devil Rays. Huckaby, who was with Triple-A Las Vegas last year, has played in the Majors with the Diamondbacks, Blue Jays, Rangers and Red Sox.
The complete list of non-roster players invited to camp:
PITCHERS (8) -- Roman Colon, John Foster, Roberto Giron, Ben Hendrickson, Nomo, Matt Peterson, Chi-hui Tsao and Matt Wright.
CATCHERS (4) -- Adam Donachie, Damason Espino, Huckaby, Kiel Thibault.
INFIELDERS (4) -- Mike Aviles, Berroa, Smith, Mike Stodolka.
OUTFIELDERS (2) -- Chris Lubanski, Hollins.
The Royals also announced they had signed pitcher Tim Hamulack and infielder David Matranga to Minor League contracts.
Seven up for exchange: Salary arbitration figures exchanged by the Royals and seven players are expected on Friday. The seven are John Buck, Jorge De La Rosa, Esteban German, Ross Gload, Jimmy Gobble, Zack Greinke and Mark Teahen.