Invincible Season 4 Episode 4: William Returns with a New Voice and a Shocking Change
March 25, 2026
In the fourth installment of Invincible’s latest season, Mark Grayson’s circle shifts again as his best friend William comes back, but not as fans remembered. The episode seeds the bigger changes brewing beneath the surface and shows that the real trouble isn’t just the Viltrumites.
- Across the cosmos, Nolan fights to safeguard the universe from his own kin, teaming up with Thaedus, who reveals remnants of the Scourge Virus still threaten the Viltrumites. This development expands the looming threat beyond Earth and sets the stakes higher than before.
- Back on Earth, Eve’s powers are revealed to be malfunctioning because she’s pregnant. The news reframes her character arc and adds new tension to the dynamics at home as her pregnancy becomes a central thread moving forward.
- The long-awaited return of William arrives with a twist: the character is voiced by a new actor. Brandon Scott Jones steps in to replace Andrew Rannells, who had voiced William for Seasons 1–3.
- Official reasons for the recasting haven’t been disclosed. However, production timing likely played a role. Creator Robert Kirkman indicated that Season 4 kicked off immediately after Season 3 to preserve the pace, and actors’ schedules often drive such changes, especially in animation where a different actor can be slotted in without impacting the schedule as much as in live action.
- Rannells’ other commitments have kept him busy with projects like Too Much and Another Simple Favor, plus returning to Big Mouth and upcoming roles, making it difficult to align with a season that demanded steady commitment. The practical reality of animation scheduling often leads to replacing or adjusting roles to keep production on track.
- In addition to William’s recasting, there’s notable news around Powerplex: Aaron Paul did not return to the role for Season 4. Paul explained that the strain of the role was tougher on his psyche than he anticipated, and he didn’t want to continue. Kirkman later suggested that scheduling pressures in animation allow for more flexibility to adjust who lands in which role, and that Powerplex remains in the world, even if not in every episode.
- Fans have responded with mix-tuned reactions on social media. Some viewers found the new William’s voice jarring and noted it didn’t resemble Rannells’ performance, which disrupted the familiar rhythm of the show. Others pointed out that voice casting changes are common in long-running series and that fans often need time to adjust.
- Rannells himself has spoken about how William’s arc was developed, emphasizing that the character’s depth was a strong facet of the portrayal, and that the new voice carries a different energy. The discussion highlights how much a voice actor can shape a character’s identity, and why such changes tend to provoke discussion among longtime fans.
- Episode 4 is part of a run of four episodes now available on Prime Video, with Episode 5 slated to drop on April 1. For fans seeking more Invincible content, there are roundups about the strongest characters, similar series to watch, and updates on any upcoming Invincible movie.
If you’re catching up, the new dynamics between William, Eve, Mark, and Nolan’s evolving mission promise to reshape the season’s trajectory.