Because you like Robin Scherbatsky in How I Met Your Mother

Bo Dennis once dreamed of being prom queen, but then she found out that she's part of some ageless secret race that feeds on humans. See them in Lost Girl.

Ava may just be the perfect woman. So long as she can pass a Turing test. See them in Ex Machina.

Tony Stark's interests include cocktails, beautiful women, particle physics, and saving the world. See them in Marvel Cinematic Universe.

Stranded on Mars, Mark Watney is armed with quick wits, an electronic diary, disco music, and an undying resolve to make it back. See them in The Martian.

Optimus Prime is a shapeshifting sentient robot leading a team of robots to stop evil from taking over. See them in Transformers.

World domination and Superman's demise are next on Lex Luthor's to-do list. See them in DC Extended Universe.

The main priority for Nagisa Hazuki is making sure that everyone has fun. See them in Free! Iwatobi Swim Club.

If anyone can stay optimistic and friendly under harsh alien rule, it's Alyx Vance. See them in Half-Life 2.

Louise Belcher might be just a kid, but she can manipulate just about anyone with a pulse. All in the name of fun, of course. See them in Bob's Burgers.

Moving is hard for Coraline Jones; accidentally moving to a creepy mirror world just makes it harder. See them in Coraline.

A responsible kid, Hugo Cabret is still capable of flights of fancy. See them in Hugo.

Knuckles the Echidna is a 16-year-old red echidna (aka a spiny anteater) and guardian of the ancient Master Emerald. See them in Sonic the Hedgehog.