Hergé started making the comic strip series Tintin in 1929 for the children's section of the Belgian newspaper Le Vingtième Siècle, aligned with the Rexist right-wing movement. He continued on other media until his death in 1983.
As a young artist Hergé was influenced by his mentors, specifically the Abbé Wallez. This shows in his most important works, the Tintin series. As the artist develops ideologically, so does the series.
Tintin's first albums, written and drawn during the 1920s, were anti-Soviet, pro-colonialist, and anti-American. This is obvious from the first three albums, which mock the Soviets, the indigenous people of Belgian Congo and the white inhabitants of the US respectively. Hergé was young, Belgian and Catholic and published in a Catholic newspaper. These comics reflect the dominant ideology in Belgium at that time.
Things began to change with The Blue Lotus (his encounter with Tchang Tchong-Jen may have changed his mind): his vision of China is more subtle and the album can be read as anti-imperialist. The album criticizes Japanese and Western involvement in China, including the international concessions and the Japanese invasion of Manchuria. Some of the white characters portrayed express blatant racist remarks and slurs.
(Some more about the political row this album caused)
Things became more complicated later. King Ottokar's Sceptre was obviously anti-nazi: Musstler (MUSSolini-hiTLER) the dictator of Borduria tried to oust king of Syldavia Muskar XII. The situation was very similar that of Anschluss in Austria in 1938. But some albums were more controversial. The early and unfinished version of Land of Black Gold is generally considered as pro-Arab, anti-Zionist and anti-British.
A very controversial book is The Shooting Star which is about a race between two crews who are trying to reach a meteorite landed in the arctic seas. This race can be interpreted as a competition between Europeans (German occupied at that time) and Anglo-Americans. The financial backer of the Anglo-Americans has a Jewish name, although this has been changed in some editions, and Tintin flies a German plane (an Arado 196). Others say the ideology is not obvious and maybe it was done to fool censorship but it is open to debate.
Generally it is accepted that Hergé during the nazi-German occupation of Belgium tried to avoid writing controversial Tintin stories. The ones written in that period, The Shooting Star, The Secret of the Unicorn, and Red Rackham's Treasure, are all stories in which the protagonists leave the known, political world in search of treasure elsewhere.
The Calculus Affair is anti-Stalinist but there is nothing specifically controversial in it.
The Castafiore Emerald takes part for the Roma. Captain Haddock and Tintin find a gypsy community camping in a garbage dump for want of any other place they are allowed to be in . Disgusted at the community's mistreatment, Haddock invites the community to camp on his estate grounds of Marlinspike over the objections of their prejudiced butler.
Flight 714 is obviously mocking Marcel Dassault who was both Jewish and a weapon seller, this could be interpreted as anti-semitic by some but there's no reference to the fact he was Jewish. Weapons sellers are a recurring theme in Tintin, there are several (more or less obvious) references to De Havilland and Vickers Armstrong.
The last controversial album is Tintin and the Picaros; it has been seen both as left-wing and right-wing. In it, Tintin goes through profound changes. Where the fans were originally put off by cosmetic changes, this is the first album in which Tintin changes from a faceless hero to somebody of flesh and blood. Where in all earlier stories the reporter was able to change his environment for the better, here he is able to change the environment too, through revolution, no less. Or so it seems. For in the very last panel of his very last finished album, Hergé shows how the new order still has the military keeping order in the slums, of which the inhabitants are off no better and no worse.
First albums
Turn-around with The Blue Lotus
The Second World War
Post-war
Picaros
To do: