Not every actor plays a character for 15 years, but lived in Dr. Spencer Reid's skin for as many seasons. He started on CBS' "Criminal Minds" when he was just 25 years old and is the only cast member to have appeared in every episode.

Between the fan adoration and his enduring presence, the young genius Spencer — who's always got a scientific explanation or obscure fact on the tip of his tongue — has become synonymous with the series.

, but he's also the sweet one who the writers can't help but put in danger over and over again. There's a kidnapping that leads to drug addiction, someone framing him for murder and a subsequent prison sentence, and countless other traumas that are too much for one human being to bear.

Although some aspects of Gubler's life — like

— have influenced Spencer's character, ultimately, they're very different people. Case in point: Gubler can both roller skate dance. But when it comes to Spencer, Gubler likes him just the way he is.

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