I never understood why O’Hare only starred on the show as Commander Jeffrey Sinclair for the first season, and basically disappeared after that (aside from a few cameos). A newspaper review I read at the time disparaged his acting, and said that his replacement, Bruce Boxleitner, had more “star power”.

Speaking for myself, I liked both of them – but was sad to see O’Hare go.

Anyways, it appears that Michael O’Hare died a few years ago, and J. Michael Stracynski revealed that O’Hare suffered from mental issues, and his departure from the show was mutually agreed upon.

In the link, Stracynski speaks of O’Hare’s struggle to complete the first season, and of the strength he drew from the show’s fans.