The following is a list of appearances by each character, sorted by episode and order of appearance. First appearances are noted in bold. Episode counts are in parentheses.
Trivia
- To date, only two episodes have featured the entire cast of series regulars: Fallout and Godsend
- Seven Minutes to Midnight featured the fewest series regulars to date. Fewer than half of the regulars appeared: Sendhil Ramamurthy (Mohinder), Masi Oka (Hiro), Santiago Cabrera (Isaac), Hayden Panettiere (Claire), and Greg Grunberg (Matt). Jack Coleman (Mr. Bennet) also appeared, but he was not made a series regular until Six Months Ago.
- Only two series regulars have appeared in every episode to date: Hayden Panettiere (Claire), and Masi Oka (Hiro). Jack Coleman (Mr. Bennet) has appeared in every episode except Nothing to Hide; he has, however, appeared in every episode since he was made a series regular.
- Only one non-series regular has appeared in every episode: James Kyson Lee (Ando).
- Of the series regulars who premiered in Genesis, Tawny Cypress (Simone) has appeared in the fewest episodes. Leonard Roberts (D.L.) has appeared in the fewest episodes of any regular, but he did not premiere until Hiros.