Last week, the court found the two leaders and 13 other members of the radical Marxist group guilty of about 2500 crimes, including multiple murders, bombings and bank robberies.
Four defendants were acquitted.
Their convictions removed a major security threat ahead of the Athens Olympic Games next August.
Judge Michalis Margaritis, presiding over a three-judge panel, handed down sentences one by one for each of the 19 murder cases in the marathon trial.
The mastermind, Alexandros Giotopoulos, 59, found guilty of plotting 19 murders, faces a possible total of 21 life sentences, the longest term in Greek legal history, while top hitman Dimitris Koufodinas, found guilty of 13 murders, faces up to 13 life terms.
End to security threat
The Greek authorities hailed the convictions as the end of the biggest domestic security threat facing the country as it prepares to host the Athens Olympics next August.
The close-knit Marxist group carried out a series of killings and bomb attacks dating back to 1975, baffling police until a bungled bombing in 2002 led to the arrest of one member and then to further arrests.
November 17, named from the date of a 1973 student uprising crushed with tanks by the military junta that ruled Greece between 1967-74, claimed 23 killings, starting with the shooting of Athens CIA station chief Jack Welch in 1975.