The Invaders is an American SCI-FI television series created by Larry Cohen which aired on ABC for two seasons, from 1967 to 1968. Roy Thinnes stars as David Vincent, who after stumbling across evidence of an alien invasion. The aliens disguising themselves as humans and gradually infiltrating human institutions, Vincent tries to thwart the invasion despite the disbelief of officials and the general public, and the undermining of his efforts by the aliens. 

The Invaders Miniseries (1995):

In 1995, the premise was used as the basis for a four-hour television miniseries revival also called The Invaders on Fox. Scott Bakula starred as Nolan Wood, who discovers the alien conspiracy, and Roy Thinnes very briefly appeared as David Vincent, now an old man handing the burden over to Wood. The miniseries has been released in some countries on home video, edited into a single movie. The first part aired on November 12, 1995; part 2 aired on November 14, 1995 (both in two-hour time slots).

The Invaders has also been released on DVD in many countries all over the world. In North America two separate seasons have been released, in other countries, like in the UK for instance, the series has been released as a complete series. Roy Thinnes also provided audio commentary for the official The Invaders DVD releases. He has also filmed special video introductions for every episode, which are an optional "Play" feature on the episode menus. (with help from wiki)

Season 2:

1. Condition: Red
2. The Saucer
3. The Watchers
4. Valley of the Shadow
5. The Enemy
6. The Trial
7. The Spores
8. Dark Outpost
9. Summit Meeting (1)
10. Summit Meeting (2)
11. The Prophet
12. Labyrinth
13. The Captive
14. The Believers
15. The Ransom
16. Task Force
17. The Possessed
18. Counter-attack
19. The Pit
20. The Organization
21. The Peacemaker
22. The Vise
23. The Miracle
24. The Life Seekers
25. The Pursued
26. Inquisition