The 2008 Open Championship was a men's major golf championship and the 137th Open Championship, played from 17 to 20 July at Royal Birkdale Golf Club in Southport, England. Pádraig Harrington successfully defended his Open Championship title, his second; he shot four under par over the final nine holes and was four strokes ahead of runner-up Ian Poulter. Harrington was the last golfer to win the same major back-to-back for a decade until Brooks Koepka won consecutive U.S. Opens in 2017 and 2018.

Television coverage was provided as usual by the BBC in the UK, and by ABC and TNT in the United States.

World Number One Tiger Woods was the most notable absentee, as he was recovering from knee surgery following his victory at the U.S. Open.

About two-thirds of the field each year consists of players that are fully exempt from qualifying for the Open. Below is the list of the exemption categories and the players who are exempt. Each player is classified according to the first category by which he qualified, but other categories are shown in parentheses. Some categories are not shown as all players in that category had already qualified from an earlier category:

1. First 10 and anyone tying for 10th place in the 2007 Open Championship
K. J. Choi (7,15,19), Stewart Cink (7,19), Ben Curtis (3,4), Ernie Els (3,4,5,7,15,19), Sergio García (5,7,14,15), Richard Green, Pádraig Harrington (3,4,5,7), Hunter Mahan (7,15,19), Andrés Romero (5,7), Steve Stricker (7,15,19), Mike Weir (7,19)

2. Past Open Champions born between 20 July 1942 and 19 July 1948
(Eligible but not competing: Tony Jacklin, Johnny Miller, Tom Weiskopf)

3. Past Open Champions aged 60 or under on 20 July 2008
Mark Calcavecchia (15), John Daly, David Duval (4), Todd Hamilton (4), Paul Lawrie (4), Tom Lehman, Justin Leonard (7), Sandy Lyle, Greg Norman, Mark O'Meara (4), Tom Watson (28)
(Eligible but not competing: Ian Baker-Finch, Seve Ballesteros, Nick Faldo, Nick Price, Bill Rogers, Tiger Woods)

4. The Open Champions for 1998-2007