Ryan Anthony Costello (born September 7, 1976) is an American politician, lobbyist, and attorney who served as the U.S. representative for Pennsylvania's 6th congressional district from 2015 to 2019. A member of the Republican Party, he was first elected to the Congress in the 2014 midterms. Costello previously served on the Chester County Board of Commissioners (2011–2015), which he chaired from 2013 to 2015.

Costello chose not to seek reelection in the 2018 election, and was succeeded by Democrat Chrissy Houlahan. After leaving Congress, Costello became a registered lobbyist.

Costello was born in 1976 to schoolteacher parents. Costello attended Ursinus College and Villanova University School of Law.

Costello served on the Board of Supervisors for East Vincent Township in Chester County, Pennsylvania, for six years, serving as chairman for the last four. He was elected the Chester County recorder of deeds in 2008. He was elected to the Chester County Board of Commissioners in 2011. His fellow commissioners elected him as chairman of the commission in 2013, and reappointed in 2014.

When Jim Gerlach, the Republican incumbent in Pennsylvania's 6th congressional district in the United States House of Representatives, announced that he would not run for reelection in 2014, Costello chose to run for the Republican Party nomination. He faced no primary opposition. He faced Manan Trivedi of the Democratic Party in the general election. Costello defeated Trivedi, 56%–44%.

In 2016, Democrat Mike Parrish challenged Costello. Hacked material from Parrish was leaked during the campaign, but the Costello campaign took the position that they would not use the illicitly obtained materials during the election. Vincent Galko, a consultant for Costello, said, "When news broke that this material had likely been stolen by a foreign actor, we immediately said, ‘We’re not going to use it.'"

Costello was re-elected by a wide margin of 57.2 to 42.8.

For his first two terms, Costello represented a district that took in northern Chester County and western Montgomery County, then reached across Berks County to take in much of heavily Republican Lebanon County. However, in February 2018, the Pennsylvania Supreme Court released a new map for the state's congressional districts to replace a map which the court had previously struck down as a Republican partisan gerrymander. The court imposed a new map after the state legislature refused to submit a replacement. Costello was the only incumbent who retained his old district number. However, the 6th was made significantly more compact. It lost most of its heavily Republican western portion, as well as its share of Montgomery County. Instead, it now took in all of Chester County as well as most of the more Democratic portions of Berks County, including Reading. Even before the old map was thrown out, Costello had already attracted a well-financed Democratic challenger, entrepreneur and Air Force veteran Chrissy Houlahan.