Character Recommendations Based on Sheldon J. Plankton

Dory
Finding Nemo
Dory is more than a little forgetful, but she'll always remember to have your back

Frodo Baggins
The Lord of the Rings
Even the smallest person can change the course of the world, if he's brave enough

Rick Grimes
The Walking Dead
When the going gets tough, Rick gets tougher. It's a very useful trait when the world goes to hell