To solve the question of who became the first athlete to throw beyond 75 meters in the men's discus event, setting a world record of 75.56 meters in April 2025, we need to identify the correct athlete from the given options:

1. Matthew Denny
2. Virgilijus Alekna
3. Mykolas Alekna
4. Sam Mattis

The correct answer is Mykolas Alekna. Let's explain why this option is correct and rule out the others:

• Matthew Denny: Although a proficient discus thrower, there are no records or reports indicating that Matthew Denny set a world record of 75.56 meters.
• Virgilijus Alekna: A renowned discus thrower and Olympic champion, Virgilijus is known for setting great benchmarks in the past. However, the record mentioned (set in 2025) is not attributed to him.
• Mykolas Alekna: As per the latest records and information, Mykolas Alekna, who is following in the footsteps of his father, Virgilijus Alekna, achieved a record throw of 75.56 meters in April 2025. This achievement made him the first athlete to surpass the 75 meters mark in the men's discus event.
• Sam Mattis: A well-known name in discus throwing, but he is not credited with this particular world record.

By analyzing the options, it's evident that Mykolas Alekna is the athlete who set this world record. This conclusion is based on factual reports and updates from athletics records in 2025.