diff --git a/services/worker/src/workers/thumbnail.js b/services/worker/src/workers/thumbnail.js
new file mode 100644
index 0000000..da103e0
--- /dev/null
+++ b/services/worker/src/workers/thumbnail.js
@@ -0,0 +1,59 @@
+import { join } from 'path';
+import { unlink } from 'fs/promises';
+import { tmpdir } from 'os';
+import { query } from '../db/client.js';
+import { downloadFromS3, uploadToS3 } from '../s3/client.js';
+import { extractFrameAtTime } from '../ffmpeg/executor.js';
+
+const S3_BUCKET = process.env.S3_BUCKET || 'wild-dragon';
+
+export const thumbnailWorker = async (job) => {
+  const { assetId, proxyKey, outputKey } = job.data;
+
+  const tmpDir = tmpdir();
+  const inputPath = join(tmpDir, `thumb-input-${job.id}.mp4`);
+  const outputPath = join(tmpDir, `thumb-output-${job.id}.jpg`);
+
+  try {
+    // Download proxy from S3
+    job.updateProgress(10);
+    console.log(`[thumbnail] Downloading ${proxyKey} for asset ${assetId}`);
+    await downloadFromS3(S3_BUCKET, proxyKey, inputPath);
+
+    // Extract frame at 5 seconds
+    job.updateProgress(40);
+    console.log(`[thumbnail] Extracting frame for asset ${assetId}`);
+    await extractFrameAtTime(inputPath, outputPath, '00:00:05');
+
+    // Upload to S3
+    job.updateProgress(70);
+    console.log(`[thumbnail] Uploading to ${outputKey}`);
+    await uploadToS3(S3_BUCKET, outputKey, outputPath);
+
+    // Update database
+    job.updateProgress(90);
+    console.log(`[thumbnail] Updating asset record for ${assetId}`);
+    await query(
+      'UPDATE assets SET thumbnail_s3_key = $1 WHERE id = $2',
+      [outputKey, assetId]
+    );
+
+    job.updateProgress(100);
+    console.log(`[thumbnail] Asset ${assetId} thumbnail complete`);
+
+    return { assetId, outputKey };
+  } catch (error) {
+    console.error(`[thumbnail] Error processing asset ${assetId}:`, error);
+    throw error;
+  } finally {
+    // Cleanup
+    try {
+      await Promise.all([
+        unlink(inputPath).catch(() => {}),
+        unlink(outputPath).catch(() => {}),
+      ]);
+    } catch (err) {
+      console.error(`[thumbnail] Cleanup error for job ${job.id}:`, err);
+    }
+  }
+};