Thomas was projected to be a long-term starter when he signed a four-year deal in 2013. But a torn right quad ended his 2013 season. He re-injured the quad during training camp in 2014 and was activated from the physically unable to perform list Friday.
Pendleton was a backup with Indy in 2013. He spent last season on injured reserve.
Indy also released offensive lineman Harland Gunn, Tyler Hoover and Brandon Vitabile; linebackers Nicklas Haag, Zack Hodges and Justin Shirk; receivers Ryan Lankford and Ezell Ruffin; tight end Justin Sinz and running back Abou Toure.
Cornerback Tevin Mitchell went on injured reserve. Cornerback Donald Celiscar will revert to injured reserve if he clears waivers.