Already solid on defense, the Dallas Cowboys officially added another athletic playmaker on Friday afternoon as they signed first-round safety Roy Williams to his first NFL contract.

Penciled in as a starter from the moment the Cowboys selected him with the eighth pick overall, the former Oklahoma star will team with perennial Pro Bowl performer Darren Woodson to potentially provide Dallas with one of the league's premier safety tandems.

Williams signed a seven-year contract that will void to five seasons if he simply reaches minimum playtime incentives. The aggregate signing bonus and second-level option bonus which is due next spring is worth $9.3 million. The per-year average for the deal, negotiated by IMG Football partners Tom Condon and Ken Kremer, is $2.653 million.

One of the college game's most notable defenders over the past few years, Williams has the hitting skills of a linebacker but enough range to be effective in coverage as well. He likes to play close to the line of scrimmage, down "in the box," and regularly gets very involved in run defense.

Despite his size (6-feet-0 ½, 219 pounds, Williams is deceptively fluid and has adequate burst to the ball. He seems to always be in a natural hitting position, strikes a rising blow, and doesn't slide off many tackles.

"He's just a very active guy," coach Dave Campo said, "and we'll figure out ways to take advantage of some of the unique things he can do for us."

Williams, 21, was a two-time All-American for the Sooners. He played in 38 games and started 29 of them and totaled 269 tackles, nine interceptions and 47 passes defensed.

The Cowboys also signed their second-round picks -- center/offensive guard Andre Gurode and receiver Antonio Bryant -- and third-round pick, cornerback Derek Ross, to seven-year deals.

The Cowboys earlier this week signed their other five draft picks: fullback Jamar Martin, cornerback Pete Hunter, offensive lineman Tyson Walter, receiver DeVeren Johnson and tight end Bob Slowikowski.

Len Pasquarelli is a senior writer for ESPN.com. Information from The Associated Press was used in this report.