Background
Celtic's first crest, was the Celtic Cross, as was seen on the first strip. However advertisements of Celtic in the early years, showed a harp against a blue background. The team also wore a strip with a large shamrock as the badge in the fifties, then the strips were without a crest until the late seventies, when the four leaf clover became the emblem, which is still used to present day. The Celtic Cross did make an appearance again in the "Centenary Year" and in 2003, to celebrate 100 years of the hoops.
Post 1995 Badge
The current badge, as below, is an amendment of the previous badge after the takeover, as in 1995 the club changed to being a Public Limited Company from being a private limited company, hence the old name around the badge had to change. The only significant change was that the name around the badge now stated "The Celtic Football Club" as against "The Celtic Football and Athletic Coy. Ltd" previously.
During the amendment, there was even consideration by Fergus McCann ( the then Chief Executive) of possibly changing the crest at one short point, but thankfully was never taken any further
see article.



Pre-1995 Prior to becoming a PLC, the full previous company name was used as below "The Celtic Football & Athletic Coy. Ltd" ("Coy." as in Company). The Athletic aspect covered that in the original days the board likely wished to attract other events to the club as well as football to broaden the club's mandate as welll as to generate revenue (e.g. cycling).

Centenary In season 1987-88, to celebrate the club's centenary the club did a one-off redesign of the badge reverting it to include the old Celtic Cross which was the symbol on the original Celtic badge when the club was formed back in 1888.

Lisbon anniversary badge (following badge was put on the Celtic home top in season 2007/08 to celebrate the 40th anniversary of the Lisbon Lions victory in 1967)



Articles
Links
Esporte Fino
(Translated, 6 Feb 09
Link)
This Friday ESPORTE FINO blog discloses the ten best looking football team badges in the world. On Monday positions 50 to 41 were revealed and today we reveal the top ten football badges in the world as voted by the blog over the last few months.
The competition started with the blog team making a short-list of team badges as our chosen judges would have gone crazy if they had to look at all the team badges from all the teams on the planet. The preliminary selection was made with help from journalist and historian Rodolfo Rodrigues, author of the book Badges of Football Teams of the Entire World. He whittled it down to 128 badges from 45 countries.
With these chosen finalists, the second phase of the project was to invite journalists and design specialists to judge the badges. All were informed that the idea was to choose the best looking badge, independent of their support for the clubs. The judges who participated in the election, plus four judges from ESPORTE FINO, were: Everaldo Marques (ESPN Brazil), Helena Jacob (journalist, graphical teacher of design and master in semiotics), Mauricio Noriega (SporTV), Mauro Beting (Bandeirantes Radio, TV Band, BandSports) and Rodolfo Rodrigues (journalist and historian, author of the book, Badges of Football Teams of the Entire World).
First placed badge on each judge’s list received 60 points, second received 49, third, 48 and so on with 50th placed badge receiving 1 point. We now reveal the top ten badges of the vote as homage to Luiz Fernando Bindi, journalist, a great specialist in club badges who died prematurely in July of 2008.
Top 31. Botafogo
2.
Celtic3. Juventus