Butler, 26, split the 2012-13 season between the Predators and New Jersey Devils, combining to total four goals and 11 points in 34 games. Butler previously played three seasons with the Ottawa Senators.
Brennan, 24, split last season between the Panthers and Buffalo Sabres, combining to total three goals and 10 points in 29 games. Brennan was a second-round pick by the Sabres in the 2007 NHL Draft.
Each player can become a restricted free agent this summer.
Philadelphia is where I started my NHL career and this is where I want to be so I am really happy. This definitely gives me a lot of confidence by the Flyers showing that they have confidence in me. I know they want to see me get better as a player and this is the place to do it.
— Zac Rinaldo to the Flyers website on signing a two-year contract extension with Philadelphia