Starr, who was not in the original series, will join the cast as Lou "Cobb" Cobbler, another '09er returning for the school's 10-year reunion. Marino will reprise his role as private detective Vinnie Van Lowe.
"I'm so incredibly excited to work with Rob and Dan and Kristen and Enrico once again!" Starr said in the announcement. "Each one a treasure in a flesh casing."
Marino left his message, via his character, in the video below:
The Kickstarter campaign for the Veronica Mars movie raised nearly $6 million when it launched in April. Returning castmembers include Jason Dohring, Enrico Colantoni, Percy Daggs III, Chris Lowell, Francis Capra, Tina Majorino, Amanda Noret, Sam Huntington, Max Greenfield and Daran Norris
Production on the film began earlier this month.