Because you like Troy Bolton in High School Musical
Captain Spock is on a five-year mission exploring the final frontier and boldly going where no man has gone before. See them in Star Trek.
Walter White's knowledge of chemistry allows him to cook astoundingly pure meth, leading to a rapid – albeit tumultuous – rise in the criminal drug world. See them in Breaking Bad.
It doesn't matter how noble or brave he is. Jon Snow is a bastard, and people don't let him forget it. See them in Game of Thrones.
When the going gets tough, Rick Grimes gets tougher. It's a very useful trait when the world goes to hell. See them in The Walking Dead.
You don't teach a class called "How To Get Away With Murder" without knowing a thing or two about getting away with things. See them in How to Get Away with Murder.
Wei Shen is an undercover cop on a mission for justice (or at least vengeance). See them in Sleeping Dogs.
Misato Katsuragi is never without a beer in her hand or her pet penguin by her side. See them in Neon Genesis Evangelion.
For Dana Scully, sometimes looking for extreme possibilities makes you blind to the probable explanation right in front of you. See them in The X-Files.
Tina Belcher is on the cusp of puberty, and she has no shame when it comes to boys, butts, and brassieres. See them in Bob's Burgers.
Alex DeLarge likes his favorite milk-based, drug-laced cocktail. It helps him get in the mood for a night of "ultra violence." See them in A Clockwork Orange.
Arthur Dent is an incredibly normal man on an incredibly abnormal adventure. See them in The Hitchhiker's Guide to the Galaxy.
Daenerys Targaryen will take what is hers with fire and blood. Thankfully, she has some dragons by her side. See them in Game of Thrones.