The Dallas Stars were busy on the first day of free agency.
Fiddler gets a a three-year, $5.4 million contract. Pardy received a two-year, $4 million deal, and Dvorak was signed to a one-year, $1.5 million deal. Souray signed a one-year, $1.65 million deal.
Ryder, 31, had 18 goals and 23 assists in 79 games in 2010-11. He had 17 points (8 goals, 9 assists) in 25 playoff games.
Ryder, a right shot, has scored 30 goals twice in his NHL career and played with Stars center Mike Ribeiro in Montreal.
"We're very excited about the additions we made," Stars general manager Joe Nieuwendyk said. "We identified the players we wanted to acquire and were able to get them. We've added six good players to our club and we feel we have improved our overall depth. We did a lot of research, and today was an important day for us."
Dallas is expected to lose center Brad Richards, maybe the most highly coveted free agent on the market. The Stars will be unable to re-sign him while in the midst of an ownership change and bankruptcy.
Fiddler, 31, has played the past two seasons in Phoenix. He had 22 points (6 goals, 16 assists) in 71 games last season. Fiddler is known as an excellent checking line center and penalty killer. He's solid on the faceoff as well, winning 53.9 percent of his draws last season. He made $1.1 million last season.
Dvorak, 34, played with both Atlanta and Florida last season, registering 22 points (7 goals, 15 assists) in 66 games. He's a dependable two-way player, who made $1.8 million last season.
Pardy, 27, played 30 games with Calgary last season, registering one goal and six assists.
He's 6-foot-4, 206 pounds and is a defensive defenseman who plays a simple game. He has 26 points (4 goals, 22 assists) in 147 career NHL games.
Pardy, who made $700,000 last season, played under new Stars coach Glen Gulutzan in Las Vegas (ECHL) in 2005-06.
Dowell played in a career high 79 games for the Blackhawks last season, registering six goals and 15 assists. The 26-year-old gets an $800,000 one-way contract.
Earlier this week, Souray was placed on unconditional waivers by Edmonton, where he had one season left on a $27 million, five-year deal signed in 2007. He played 40 games last season for Hershey in the American Hockey League, but none for the Oilers.
Mark Stepneski covers the Stars for ESPNDallas.com. Information from The Associated Press was used in this report.