Walter Koenig, Ensign Chekov on original 'Star Trek' series, dies at 90

1. 1966 to 1969
   'Star Trek' television series airs on NBC
2. starting in 1979
   Koenig begins playing Chekov in seven 'Star Trek' movies
3. 1980
   Koenig writes the 'Star Trek' book 'Chekov's Enterprise'
4. 1990s
   Koenig makes occasional appearances in the syndicated TV series 'Babylon 5'
5. Monday
   Koenig dies at his home in North Hollywood, surrounded by his daughter and niece

“My heart is heavy”