George Pompidou. Walldenstrom disease got him - then the very same illness also got the Shah, Golda Meir, and Algeria's Boumediene. Pretty unbelievable, when you think about it.
Pompidou lasting into April 1976 (since his 7-years mandate started a 1969 reboot of French presidential elections, when de Gaulle threw the towel) would have a massive impact everywhere - Giscard& Chaban-Delmas OTL candidacies related to Pompidou death, would be gone; or different, in 1976 or 1983. Also Chirac & Balladur long term fates - and this is only the french Right.
Miterrand, Roccard and communists, on the left, would try their chance in 1976.
Would Pompidou try a second mandate (that would be April 1976 - April 1983) ? once again, having him lasting so long would impact all the aforementioned people on the Right and Left... Mitterrand cancer may not wait, for a start. Others would grow too old for a presidential run.
The OTL sequence triggered by Pompidou death, was as per follow.
1- in 1974 Chirac screwed Gaullist Chaban-Delmas in favor of non-Gaullist, center-right Giscard, for two reasons.
a) Chirac coldly calculated that, facing Mitterrand, Giscard had better chances than Chaban, and he was proven right
b) Giscard rewarded Chirac with the PM job.
2- Giscard then screwed and humiliated his PM Chirac, who never pardonned. Chirac endured it for two years then in the summer 1976 slammed the door, re-crated the RPR gaullist party, and went on in MArch 1977 as Mayor of Paris
3- Chirac screwed Giscard for Mitterrand in 1981 (!) just for the sake of vengeance
4- Miterrand then proceeded to methodically screw Chirac, twice: as PM in 1986 and in the 1988 Presidential election.
Pompidou living as president until 1976 completely threw that OTL sequence into chaos.