Matterhorn is used for Don Pendleton’s The Executioner series from Pinnacle Books. Shown above is the first printing of the third book, Battle Mask, published in April 1970. The shorter bar in the first letter of the tt combo and the shorter bottom bar in E are likely contextual modifications. This masthead became the standard for the series starting with the the seventh book and the series’ many reprints until sometime in the late 1970s, several of which are shown below.
From Wikipedia:
The Executioner (a.k.a. Mack Bolan) is a monthly men’s action-adventure paperback book series (published from 1969–2020) following the exploits of the character Mack Bolan and his wars against organized crime and international terrorism. The series has sold more than 200 million copies since its 1969 debut installment, War Against the Mafia.
The regular series includes 464 novels (as of December 2020 when the series ended). […] The Executioner was created and initially written by American author Don Pendleton, who penned 37 of the original 38 Bolan novels (he did not write #16).