Thunderbolts* will feature the MCU debut of The Sentry, with Lewis Pullman stepping in to play "Bob" after Steven Yeun was forced to drop out due to scheduling issues. 

The latest trailer made it clear that he'll be the movie's big bad, though the character has a very complicated and convoluted history on the page. Essentially retconned into the Marvel Universe's Silver Age, he's since become one of this world's greatest heroes and villains...and even died a few times for good measure. 

It's hard to say whether Marvel Studios has plans for the character beyond this movie. Still, whether you're a hardcore fan of The Sentry in need of a refresher or unsure who he is and why you should care, we have you covered with this handy guide.

To take a look through this breakdown, simply click on the "Next"/"View List" buttons below.

5. The Sentry's Origin Story

For the longest time,...