Now, it's a foregone conclusion that the 11-time Pro Bowler will be elsewhere for the 2012 season, as the two sides officially parted ways on Wednesday.
Manning, who was taken first overall by the Colts in the 1998 draft, compiled a 141-67 record in 13 seasons in Indianapolis, including a Super Bowl in 2006. The four-time MVP has 399 career touchdowns and a 64.9 completion percentage, and he sits just 172 passing yards shy of 55,000 for his career.
Unsurprisingly fans, NFL players and even celebrities have reacted strongly to the news, particularly in the Twittersphere. Check out some of those reactions below.