The third season of the Sibling Rivalries series ran from May 22 to July 31, 2015. This is the only season to end in an odd number of comics.
The season finale is very significant to the franchise, as it introduces Hector Wilson, who later becomes the McReary siblings' new step-father in a life-changing event.
Originally, Season 3 would have been very short and only contained the comics "Best Brother" to "Meet The Robots!", which was four comics. However GTA Nerd then split the originally 16-comic long Season 4 in half and gave this series the first eight comics to this season. "Best Brother" and "Do You Get The Message?", which were originally the first two comics of this series, were then added as the last Season 2 comics.
- Patrick McReary (9/9)
- Francis McReary (9/9)
- Gerald McReary (9/9)
- Derrick McReary (9/9)
- Kate McReary (9/9)
- Maureen McReary (8/9)
- Angel Chacon (8/9)
- Salvador Real (9/9)
- Joel Gonzales (3/9)
- Spencer The Dog
- Steve Madison
- Mark Leone
- Hector Wilson
- Trevor Johnson
- Officer Charlie Macias
- Officer Fred Miller
- Not Afraid (Of Losing My Concert Tickets) (Release date: July 14, 2014)
- Meet The Robots! (Release date: August 3, 2014)
- A Family Pet (Release date: August 4, 2014)
- Field Trip Gone Wrong! (Release date: August 11, 2014)
- Patrick McReary: School President (Release date: September 8, 2014)
- House Party (Release date: January 4, 2015)
- The Pool Date (Release date: July 1, 2015)
- Fourth Of July (Release date: July 7, 2015)
- Like Father, Like Sons (And Daughter) (Release date: July 31, 2015)
- Packie and Gerry are the only siblings that do not wear their trademark clothes on the cover for this season.
- Season 3 has a unique cover, which has the names of every comic up to "Dodgeball Mishap" behind the five siblings. The three prequels were also included, though at the time the cover was created, none of them were released yet.
- This is the longest season in terms of how long it took for all comics to be completed, due to the lengthy hiatus from January to July 2015.