Years ago, back when the CW was still the WB, there was a failed pilot for an Aquaman series. It was 2007, and a young Justin Hartley was all set to portray the fish-talking hero. I remember seeing a preview for it and thinking "when did Ted Mosby bleach out his hair and hit the gym so hard?" But it wasn't Ted Mosby (Josh Radnor) at all; it was a lookalike!
What's funny about this scenario is that the how i met your mother gang often talks about their own doppelgangers, and in this week's episode they finally discovered the fifth one - a Barney lookalike. Ted's doppelganger was played by Josh Radnor, but he could have just as easily been played by this guy. By the way, my roommates and I found a movie on Netflix Instant Watch called Spring Breakdown that starred Justin Hartley and Amy Poehler, Rachel Dratch, and Parker Posey. It was nutso because it had clearly been funny once, before they edited it down to PG-13. Now it is a weird one.